Chapter XIII: Section 4: (stenopterobia)

SURIRELLA ANCEPS LEWIS

Frustule linear, straight or nearly so; valve sigmoid with rounded apices; costæ marginal, nearly obsolete; striæ distinct, about 15 in 10 µ; pseudoraphe wide. L. to 320 µ.

Hammonton Pond and Tom's River, N. J.

Pl. 34, Fig. 2.

SURIRELLA INTERMEDIA LEWIS

Frustule linear, straight, widened at the truncate ends; valve linear, sigmoid, tapering to the sub-acute ends; costæ about 5 in 10 µ; striæ about 20 in 10 µ. L. variable.

Hammonton Pond, N. J.

Pl. 34, Fig. 3; Pl. 39, Fig. 9 (zone view).

This, perhaps, is forma sub-acuta Fricke.

Fig. 7, Pl. 34, is probably a small form of S. intermedia, from Willistown, Pa. It resembles a Nitzschia.

SURIRELLA DELICATISSIMA LEWIS

Frustule linear, rounded at the ends; valve linear-lanceolate, sometimes very slightly constricted in the middle, with acute apices; costæ, 5 in 10 µ; striæ about 20 in 10 µ; pseudoraphe well defined, lanceolate. L. to 90 µ.

Fresh water. Newtown Square.

Pl. 34, Figs. 5 and 6 (small forms).

SURIRELLA ARCTISSIMA A. S.

Valve linear, tapering to the sub-acute ends; costæ marginal, 5 in 10 µ; striæ, 18 in 10 µ; pseudoraphe not evident. L. 184 µ.

May's Landing, N. J.

Pl. 34, Fig. 4.

Fig. 10, Pl. 39, is a small form from Newtown Square, Pa., in which the length is 86 µ, the costæ 5 and the striæ 16 in 10 µ.

PODOCYSTIS KUETZ. (1844)

(pous, a foot, and cystis, a bag)

Frustules cuneate, similar to Surirella, but attached by short stipes to other algæ; valve obovate.

{129}PODOCYSTIS ADRIATICA KUETZ.

Valve nearly symmetrical, obovate, with transverse costæ about 4 in 10 µ, alternating with double rows of coarse puncta; median line distinct, linear. L. 43 µ.

_Podocystis americana_ Bail.

Hell Gate, N. Y.

Pl. 40, Fig. 6.

CYMATOPLEURA WM. SM. (1851)

(cuma, a wave, and pleura, a side)

Valve elliptical; surface transversely undulate, with short, marginal costæ. Frustule in zone view linear, with undulated sides.

Auxospore formation as in Surirella.

CYMATOPLEURA SOLEA (BRÉB.) WM. SM.

Valve oblong, with cuneate apices, constricted in the middle; costæ about 6 in 10 µ; striæ, 10 in 10 µ; pseudoraphe scarcely visible. L. 50-300 µ.

Blue clay. Common in the Hudson River.

Pl. 34, Figs. 8 and 9.

CYMATOPLEURA ELLIPTICA (BRÉB.) WM. SM.

Valve elliptical; marginal costæ short, 3 in 10 µ; striæ delicate, 18 in 10 µ; undulations four or more. L. 70-140 µ.

Blue clay.

Pl. 37, Fig. 1.

_Forma spiralis._--Valve ovate, swelled into curved ridges at the lower end, with a contraction of the valve.

Port Penn, Delaware River.

Pl. 37, Fig. 2.

CYMATOPLEURA MARINA LEWIS

Frustule linear, with numerous undulations, ends apiculate; valve linear-lanceolate, with acute ends; striæ transverse, punctate at unequal intervals, from 16-18 in 10 µ. L. 43 µ.

East River, N. Y.

Pl. 37, Figs. 3 and 4.

Lewis states that the ends are more or less truncate. I do not find them so.

CAMPYLODISCUS EHR. (1841)

(campulos, curved like a saddle)

Valve orbicular or sub-orbicular, with costæ or punctate rays converging from the circumference toward the hyaline centre, which sometimes appears like a pseudoraphe. Frustule of two saddle-shaped valves at right angles to each other. The zone view may be of almost any shape according to position.

Endochrome consists of two bands, each lining the inner surface of each valve. Auxospore and conjugation unknown.

{130}CAMPYLODISCUS ECHENEIS EHR.

Valve sub-orbicular, saddle-shaped; costæ indistinct, short, marginal; rows of round or elongated puncta converge toward the lanceolate, hyaline median space. Diam. 80-140 µ.

_Campylodiscus argus_ Bail.

Blue clay. Reservoir at Thompson and Twenty-sixth Sts., Phila.

Pl. 37, Fig. 6.

This form, usually considered as brackish and marine, is occasionally found in fresh water. According to Deby, it is fossil in the "Champlain deposit of N. A."

CAMPYLODISCUS HIBERNICUS EHR.

Valve irregularly orbicular; costæ, 40-60, about 2 in 10 µ, wide at the margin and attenuated toward the centre which is somewhat quadrate; the radials rough with minute apiculi.

Pensauken, N. J., artesian well.

Pl. 37, Fig. 5.

{131}APPENDIX

COLLECTION AND PREPARATION OF DIATOMS

It is assumed that every student of the Diatomaceæ has a general knowledge of the collection, preparation, mounting and examination of material. For the novice, however, the following methods, used by the author for many years, may be of service.

_Collection of Fresh-water Material._--The yellow film on the inside of aquaria always contains small species. Stems of water-plants near the shores of ponds and the submerged roots, the brownish coating of rocks in streams and water-falls, fountains, and water-troughs, are prolific. At all times of the year, some diatoms may be found in a thin layer upon the mud of rivers or creeks. In the spring, brown patches of mud, filled with bubbles, floating near the shore in ponds, or coming down with the current in rivers, are rich in various forms. Within the limits assigned to our district, I have made collections in the following localities: Schuylkill River, including the region near Fairmount Dam, several reservoirs and the water-supply; the Wissahickon and Fairmount Park, Darby, Crum and Ridley Creeks, the Neshaminy and the Brandywine; meadow pools and rivulets near the city; the upper Delaware, the Water Gap and numerous cascades northward; the Shawangunk Mountains and the Poconos; many parts of New Jersey along the coast; the Pine Barren region, the Hammonton, Atsion and Kirkwood Ponds and the swamps near Atco.

In the collection of fresh-water material, it is well to be provided with a number of small bottles. Take a handful of the water-plants or algæ, and squeeze the material into the bottles, or, lacking a bottle, wrap it in paper. With a small forceps it is possible to detach minute quantities of a pure gathering which may not need further preparation beyond burning to a red heat on the cover-glass before mounting. A malacca cane, with extending rod to which may be screwed a bottle, net, spoon or hook, is useful on a long trip. If it is impossible to separate the thin film of diatoms from the mud in the bed of streams, dip up the surface mud with one bottle, allow to settle a few minutes, then pour off the supernatant liquid, which will be comparatively free from sand, into another bottle. It must be confessed, however, that the mud in streams near Philadelphia contains a large quantity of fine mica which, in some instances, it is impossible to remove.

_Collection of Marine Material._--Shell scrapings, the stomachs of fish, marine algæ, especially the brown and red algæ, the hulls of vessels, mud from anchors and dredgings, are all sources which may prove valuable. In the sand ripples, after the tide recedes, a yellowish-brown deposit will be noticed. This should be taken up carefully with a spoon and placed in a bottle; the sand will settle at once and a very pure gathering will be held in suspension in the water. Such collections may be made along the entire coast of New Jersey on sunny days in summer. In salt meadows near Absecon and Hackensack, large quantities of diatoms, including Pleurosigma, may be obtained in the yellow scum floating on the surface.

_The Blue Clay Deposit._--The blue clay occurs as a pre- or post-glacial deposit in the bed of the ancient Delaware River, and, at depths varying usually from fifteen to forty feet below the surface, has been obtained from artesian wells at Pavonia, Pensauken and Gloucester, N. J., also at Port Penn on the Delaware, and especially from the dredgings {132}made by the removal of Smith's Island opposite the city. In the city proper, it may be stated briefly that material may be found in a stratum of very light blue clay at a depth varying from twenty to sixty feet in many places south of Arch St. east of Broad St., and also along the beds of ancient rivulets near Tioga St., at Sixteenth St., and in certain other places which were probably subject to tidal overflow. One of the best collections was made along the bank of the Schuylkill at the east end of Walnut St. Bridge, at a depth of thirteen feet below the surface. Excavations for the Reading Terminal and the Subway and several buildings, as the Bingham House, have furnished numerous specimens.

_Cleaning the Material._--Some gatherings may be so pure as to be ready for mounting when treated with dilute alcohol and oil of cloves. If, when gathered, the diatoms are immersed in a saturated solution of picric acid for several days, they may be stained with carmine or methylene blue, or whatever may be required to emphasize the contents of the frustules, including the endochrome and the pyrenoids. After staining, pass as rapidly as expedient through the treatment with dilute alcohol and oil of cloves, and mount in benzol balsam, avoiding heat. A hot solution of mercuric bichloride is sometimes used for the preservation of the endochrome, although washing is needed before mounting. For the particular stain considered best for certain details of structure, it will be advisable to consult works on Micro-Chemistry or Heinzerling (_l. c._). The stains of most importance are carmine, methylene blue, hæmatoxylin, gold chloride and Bismarck brown.

Whatever method may be used in staining, the identification of forms is impossible, in most cases, unless the valves are carefully cleaned and the cell-contents destroyed. For this purpose provide a casserole holding from five to eight ounces, an iron tripod stand with alcohol lamp, several six-inch test-tubes, preferably those with a standard base, fitted with pure rubber corks. Take the material as free from twigs, dead leaves, sand, and other matter as possible, place it in the casserole, and add about the same quantity of nitric acid. Boil for twenty minutes and then add about half a teaspoonful of powdered bichromate of potash, stirring with a glass rod. Then take a beaker-glass partly filled with water and pour into it slowly the liquid which has been allowed to cool a short time, whirling the casserole to cause the concentration of sand in the centre. Allow the material to settle for half an hour or longer, according to the amount of diatoms and their size. Pour off the water, add more water, and place in a test-tube. Repeat the decantation, shaking the test-tube, closed with a rubber cork, vigorously each time. From time to time whirl the diatoms in the casserole and throw away the sand collected in the centre. By repeating the decantation, shaking and whirling, the deposit will be found to consist almost entirely of diatoms. It may be necessary to repeat the boiling in the acid and bichromate. If, however, any detritus other than sand is noted, boil in sulphuric acid and add from time to time minute pinches of powdered chlorate of potash, being careful to protect the eyes by holding a piece of glass before them; otherwise the explosions which occur are likely to throw some of the boiling acid into the eyes and destroy the sight. The material, when clean, should be white or, in the case of Synedra, yellowish. It is quite easy to construct a box fitted with the proper apparatus for boiling and provided with a glass door for observation, and a method of introducing the chlorate of potash through a small aperture or tube. The box may be placed in the garden or fastened outside of a window so that the poisonous fumes may be carried off.

An excellent method, in the case of larger forms, is to boil the material already cleaned by the acid in water to which a few shavings of coarse brown soap are added. The difference in density will hold in suspension any flocculent matter, and while many of the smaller {133}forms will not settle, the others will be perfectly cleaned. When satisfied with the cleaning, preserve the stock material in part alcohol and, in using, pour into a smaller bottle the amount required, replace the dilute alcohol with distilled water, and mount as directed. It often happens that gatherings are made consisting almost entirely of sand. Attempts at cleaning in the usual way will cause the loss of nearly all of the diatoms. In this case, after the material has been treated with acid until nothing remains but sand and a few diatoms, the mechanical finger must be used.

In the cleaning of marine deposits, various methods may be required. In the case of partly siliceous species, washing in pure water repeatedly is all that can be done. The larger and heavier diatoms may be separated from the sand by elutriation or by whirling in a casserole, by rocking in a shallow dish the shape of a watch crystal, or by pouring slowly over a strip of plate-glass at least two feet in length inclined at an angle of thirty degrees. The sand will cling to the glass, while the greater portion of the diatoms will run off. Where particles of shells or foraminifera are present, a preliminary boiling in hydrochloric acid is advisable. In all marine gatherings, the salt should first be washed out before proceeding with the cleaning.

For hardened masses of clay and for fossil deposits, it is necessary to boil in carbonate of soda and follow with the acid treatment. Citric acid and acetate of potash used alternately in boiling may be tried. Soaking for a time in acetate of potash and allowing the material to deliquesce for a week before further process, has proved successful in some instances. The repetition of several methods and the gentle breaking of the harder masses with the point of a needle will disintegrate almost any diatomaceous earth, but, as a last resort for refractory deposits, boil in pure water, add a piece of caustic potash about the size of a pea, continue the boiling not more than thirty seconds longer, and pour instantly into dilute hydrochloric acid; otherwise the diatoms will be destroyed. Afterwards proceed with the usual treatment.

_Slides and Covers._--Take half an ounce of No. 1 covers, circles, and place them in a wide-mouthed bottle. Add a portion of the following mixture (Dr. Carl Seiler's formula):

Bichromate of potash 2 oz.
Sulphuric acid 3 fl. oz.
Water 25 fl. oz.

Shake the bottle in order that the surfaces of the covers may be fully exposed to the action of the acid, and set aside for several hours. Decant the solution, add water repeatedly until all traces of the mixture are removed, and keep the circles in the bottle in fifty-per cent. alcohol. When needed, take out a circle with forceps and dry on a linen cloth.

The slides may be treated in the same way, or they may be easily prepared by immersion in a solution of washing soda, and then washed and dried. This process may be used in cleaning the balsam or styrax from old slides.

_Preparation of Strewn Mounts._--Place several covers on the mounting stand. With a dipping tube, cover each circle with distilled water, and add a small drop of the prepared diatoms, being careful to avoid any vibration of the stand. Heat the stand until small bubbles begin to appear, remove the lamp, and allow the water to evaporate. If the above method is carefully followed, the diatoms will be deposited in an even layer, provided the material is not too dense. Take a slide, centre it, and place a small amount of styrax on the centre. Invert the prepared cover, and gently place it upon the styrax. Heat the slide {134}on the mounting stand until the styrax bubbles and then allow to cool. If bubbles still remain, heat again until they disappear. It is well to mount several slides more than required, as some may be imperfect.

_Preparation of Selected Mounts._--Take a slide, place a minute quantity of beeswax on two places at a distance apart nearly equal to the diameter of the cover used. Place a cover on the wax and press it down flat, or sufficiently to keep it in position. Dip a fine needle into the following cement:

Glacial acetic acid 12 drachms
Gelatine 2 drachms
Alcohol 1 drachm

This is made by adding the acid to the gelatine in a water-bath and then the alcohol, and filtering. Apply the moistened needle to the centre of the cover and spread as small a quantity as possible in a thin layer. Now place the slide upon the turn table, centre it with respect to the position of the gelatine, and with the finest sable brush draw a circle about a tenth of an inch in diameter around the gelatine in water-color (Windsor), blue or vermilion, or in India ink. Instead of the water-color, a circle of tin-foil the size of the cover and pierced with a hole in the centre may be used, but the colored circle is to be preferred, as, when brought into view, it indicates exactly the focus required for observing the diatom.

The bottle containing the cleaned material, which has been kept in water and alcohol, should be refilled with distilled water and well shaken, when a small portion may be taken up with a dipping tube and evenly distributed over a portion of a slide and then dried. By the use of a mechanical finger, fitted with a small piece of finely spun glass attached by wax to the holder of the finger, when the microscope is focussed until the glass thread touches the diatom selected, it will adhere to the thread. Raise the body of the microscope, remove the slide containing the spread material, or move it to another part of the stage, and place the slide with the prepared cover in the same position. Now carefully lower the body-tube of the instrument until the diatom rests upon the gelatine, breathe gently upon it, remove the cover from the slide, invert it over another slide containing a drop of styrax and proceed by heating to mount as before. The size of the diatom, the amount of gelatine, and several other factors, will enter into the question of success or failure. I have, however, employed the above method and have mounted thousands of slides of selected diatoms successfully. It is necessary to avoid any air current which will cause the diatom to fall from the thread. On very cold days the glass thread sometimes becomes electrified and the diatoms will not stick; on sultry days in August in our locality the diatoms will stick too closely.

By the same method, slides of arranged diatoms can be made using a glass circle properly marked with lines in the eye-piece. Care should be taken to use glass threads more or less in proportion to the size of the diatoms. A cat's whisker is preferred by some to the glass thread. It has the advantage of not breaking, but unless it is quite short it is too flexible. If the point of the thread becomes covered with gelatine, lower it into a minute drop of water upon a separate slide, and by moving it about it will be cleaned. The diatom itself may be washed in the same way, if it is not too small.

_Instruments Required._--For collecting, in order to determine the quality of the find, any simple lens of fifteen to twenty diameters is sufficient. A Stanhope is quite useful {135}although difficult to obtain, while an achromatic triplet of sufficient power will probably be all that is necessary. For selecting with the mechanical finger, an objective of two-thirds-inch focus is the most convenient, but for determining species a one-fifth-inch is needed, an immersion objective being essential for minute forms.

No particular form of microscope is required. Any instrument having standard parts, inclination of the body to the axis, a sub-stage condenser and movable stage, will prove serviceable in nearly all investigations. For critical work, measurement of striæ and location of specimens on the slide, the large models of Bausch and Lomb leave nothing to be desired. One smaller instrument may be used for rapid examination and for selection with the mechanical finger. If the stage is supplied with a vernier, the diatoms can be located rapidly and recorded for future reference. The Zentmayer Army Hospital stand with mechanical stage is excellent. The Continental stands, convenient for laboratory work, especially in the examination of bacteria, are not so serviceable as the larger stands of American and English make. The stand especially designed by Dr. Henri Van Heurck, the celebrated Belgian naturalist, is, without doubt, admirably suited to the investigation of the Diatomaceæ. In the form of the Circuit Stage as made by Watson and Sons, of London, supplied with proper condenser and mechanical stage with vernier attachment, it has been used in the preparation of the present work with much satisfaction.

The drawings have all been made with an Abbé camera lucida, a 3 mm. objective and a No. 10 eye-piece, producing a magnification of about 800 diameters. All illustrations are from actual specimens in my cabinet or, in a few instances, from slides sent me by friends. In the measurement of striæ and puncta, the number in ten microns is stated, and will be found to be approximately correct in most of the drawings, except when the number is in excess of twenty in ten microns, in which case it is impossible to represent the markings accurately on figures of the magnification adopted. All drawings are from specimens in this locality, except in a few cases mentioned in the text.

{137}INDEX

(SYNONYMS IN ITALICS)

PAGE
Achnanthes, 58
brevipes Ag., 59
coarctata (Bréb.) Grun., 59
danica (Floegel) Grun., 60
exigua Grun., 59
inflata (Kuetz.) Grun., 59
lanceolata (Bréb.) Grun., 59
linearis forma curta H.L.S., 59
longipes Ag., 58
subsessilis Kuetz., 59

Actinella, 54
punctata Lewis, 54

Actinocyclus, 26
barkleyi var. aggregata Rattr., 27
ellipticus var. delawarensis n. var., 27
moniliformis Ralfs, 27

Actinoptychus, 24
_cellulosa_ Ehr., 24
heliopelta Grun. var.?, 25
_omphalopelta_ Ehr., 24
undulatus (Kuetz.) Ralfs, 24
vulgaris var. interrupta n. var., 24

Amphipleura, 78
pellucida Kuetz., 78
rutilans (Trentepohl) Cl., 78

Amphiprora, 68
alata Kuetz., 68
conspicua Grev., 68
_lepidoptera_ Greg., 69
ornata Bail., 68
paludosa Wm. Sm., 68
pulchra Bail., 68

_Amphitetras_,
_antediluviana_ Ehr., 32
_tessellata_ Shad., 32

Amphora, 65
acuta Greg., 66
angusta var. eulensteinii Grun., 67
_aponina_ Kuetz., 66
arenaria Donk., 67
areolata Grun., 66
coffæiformis (Ag.) Kuetz., 66
crassa Greg., 65
_eulensteinii_ A.S., 67
gigantea var. fusca A.S., 65
_insecta_ Grun., 69
lævis Greg., 66
lineolata Ehr., 66
_mucronata_ H.L.S., 69
obtusa Greg., 67
ocellata var. cingulata Cl., 67
ostrearia Bréb., 66
ovalis (Bréb.) Kuetz., 65
var. libyca (Ehr.) Cl., 65
var. pediculus (Kuetz.) Cl., 65
_plicata_ Greg., 66
_porcellus_ Kitton, 66
proteus Greg., 65
_quadrata_ Bréb., 66
robusta Greg., 65
_salina_ Wm. Sm., 66
_vitræa_ Cl., 66

Anomoeoneis, 80
follis (Ehr.) Cl., 80
serians Bréb., 80
sphærophora (Kuetz.) Cl., 80

Anorthoneis, 56
excentrica (Donk.) Grun., 56

Asterionella, 50
formosa Hass., 50
inflata Heib., 50

Attheya, 38
decora West, 38

Aulacodiscus, 26
argus (Ehr.) A.S., 26

Auliscus, 28
cælatus Bail., 29
pruinosus Bail., 28
punctatus Bail., 28
sculptus (Wm. Sm.) Ralfs, 29
_spinosus_ Christian, 29

Auricula, 69
_insecta_ (Grun.) Cl., 69
mucronata (H.L.S.) Per., 69

_Bacillaria_, 119
_paradoxa_ Gmelin, 119

Biddulphia, 31
alternans (Bail.) V. H., 33
antediluviana (Ehr.) V. H., 32
biddulphiana (Smith), 31
favus (Ehr.) V. H., 31
granulata Roper, 32
lævis Ehr., 33
_pulchella_ Gray., 31
reticulum (Ehr.), 33
rhombus (Ehr.) Wm. Sm., 32
smithii (Ralfs) V. H., 32
turgida (Ehr.) Wm. Sm., 32

Brébissonia, 79
boeckii (Kuetz.) Grun., 79
palmerii n. sp., 80

Caloneis, 81
brevis var. vexans Grun., 82
formosa (Greg.) Cl., 82
liber (Wm. Sm.) Cl., 81
permagna (Bail.) Cl., 82
var. lewisiana n. var., 82
powellii (Lewis) Cl., 83
silicula (Ehr.) Cl., 81
var. inflata (Grun.) Cl., 81
trinodis (Lewis), 81
wardii Cl., 82

Campylodiscus, 129
_argus_ Bail., 130
echeneis Ehr., 130
hibernicus Ehr., 130

_Cerataulus_
_smithii_ Ralfs, 32
_turgidus_ Ehr., 32

Cocconeis, 57
dirupta Greg., 58
pediculus Ehr., 57
pellucida Grun., 58
placentula Ehr., 57
var. lineata (Ehr.) V. H., 58
scutellum Ehr., 57
var. ornata Grun., 57

_Cocconema_
_asperum_ Ehr., 61

_Colletonema_
_neglectum_ Thwaites, 95
_vulgaris_ Thwaites, 77

_Conferva_
_biddulphiana_ Smith, 31
_flocculosa_ Roth, 36
_moniliformis_ Mueller, 16
_nummuloides_ Dillw., 1617
_rutilans_ Trentepohl, 78

Coscinodiscus, 21
argus Ehr., 23
asteromphalus Ehr., 23
var. omphalantha Grun., 23
biangulatus A. S., 23
denarius A. S., 22
excentricus Ehr., 21
var. perpusilla Grun., 21
lewisianus Grev., 24
lineatus Ehr., 21
marginatus Ehr., 22
_minor_ Wm. Sm., 14
nitidulus Grun., 21
nitidus Greg., 21
oculus-iridus Ehr., 23
polyacanthus Grun., 22
radiatus Ehr., 23
_striatus_ Kuetz., 19
subaulacodiscoidalis Rattr., 23
subtilis Ehr., 21
velatus Ehr., 22

_Creswellia_
_turris_ Grev., 18

Cyclotella, 19
antiqua Wm. Sm., 20
comta (Ehr.) Kuetz., 20
_dallasiana_ Wm. Sm., 19
_kuetzingiana_ Wm. Sm., 19
meneghiniana Kuetz., 19
var. stelligera Cl. and Grun., 20
var. stellulifera Cl. and Grun., 20
operculata (Ag.) Kuetz., 20
_scotica_ Kuetz., 18
striata (Kuetz.) Grun., 19
stylorum (Br.?) V. H., 20

Cymatopleura, 129
elliptica (Bréb.) Wm. Sm., 129
marina Lewis, 129
solea (Bréb.) Wm. Sm., 129

Cymbella, 60
affinis Kuetz., 61
amphicephala Nægeli, 61
aspera (Ehr.) Cl., 61
cistula (Hempr.) Kirchn., 62
cuspidata Kuetz., 60
cymbiformis (Kuetz.) Bréb., 62
ehrenbergii Kuetz., 60
excisa (Kuetz.) De Toni, 61
_gastroides_ Kuetz., 61
gracilis (Rab.) Cl., 64
heteropleura (Ehr.) Kuetz., 60
lacustris (Ag.) Cl., 64
lanceolata (Ehr.) Kirchn., 62
mexicana (Ehr.) A. S., 62
naviculiformis Auerswald, 60
parva (Wm. Sm.) Cl., 61
philadelphica n. sp., 63
prostrata (Berk.) Cl., 63
rhomboidea n. sp., 63
sinuata Greg., 61
triangulum (Ehr.) Cl., 63
tumida (Bréb.) V. H., 62
turgida (Greg.) Cl., 63
var.?, 63
ventricosa Kuetz., 62

Diatoma, 41
anceps (Ehr.) Kirchn., 42
_arcuatum_ Lyng., 35
_biddulphianum_ Ag., 31
hiemale (Lyng.) Heib., 42
_marinum_ Lyng., 37
vulgare Bory., 42
var. elongatum (Ag.), 42
var. grande (Wm. Sm.) Grun., 42

Dictyoneis, 78
marginata var. commutata Cl., 79
var. maxima n. var., 79
var. typica Cl., 78

Dimerogramma, 46
marinum (Greg.) Ralfs, 46
minus (Greg.) Ralfs, 47
_sinuatum_ Thwaites, 119
surirella (Ehr.) Grun., 46

Diploneis, 84
campylodiscus (Grun.) Cl., 86
crabro Ehr. var.?, 85
var. expleta (A. S.) Cl., 85
var. pandura (Bréb.) Cl., 85
var. pandurella Cl.?, 85
elliptica (Kuetz.) Cl., 84
var. _minutissima_ Grun., 85
excentrica n. sp., 85
fusca var. delicata (A. S.) Cl., 85
gemmata (Grev.) Cl., 86
gruendleri (A. S.) Cl., 85
oculata (Bréb.) Cl., 86
puella (Schum.) Cl., 85
smithii (Bréb.) Cl., 84

Ditylum, 30
intricatum (West) Grun., 30

_Echinella_
_circularis_ Grev., 40
_flabellata_ Carm., 39
_paradoxa_ Lyng., 39

Encyonema, 62

Epithemia, 111
argus Kuetz., 111
var.?, 111
_gibba_ var. _ventricosa_ Kuetz., 113
gibberula var. producta Grun., 112
_marina_ Donk., 114
muelleri A. S.?, 111
musculus Kuetz., 112
var. constricta (Bréb.) V. H., 112
_succincta_ Bréb., 112
turgida (Ehr.) Kuetz., 111
zebra var. proboscidea (Kuetz.) Grun., 112

Eunotia, 51
bactriana Ehr., 54
biceps Ehr., 53
bidentula Wm. Sm., 54
_bigibba_ Greg., 53
formica Ehr. var.?, 54
gracilis (Ehr.) Rab., 51
hemicyclus (Ehr.) Ralfs, 53
_incisa_ Greg., 52
luna Ehr., 52
lunaris (Ehr.) Grun., 53
major (Wm. Sm.) Rab., 51
nymanniana Grun., 51
pectinalis (Kuetz.), 52
var. solierolii (Kuetz.), 52
var. undulata Ralfs, 52
var. ventricosa Grun., 52
prærupta Ehr., 53
var. bidens Grun., 53
robusta Ralfs, 53
veneris Kuetz., 52

Eunotogramma, 33
læve Grun., 33

Euodia, 34
gibba Bail., 34

Eupodiscus, 28
_argus_ (Ehr.) Wm. Sm., 26
radiatus Bail., 28
_radiatus_ Wm. Sm., 32

Fragilaria, 44
arctica Grun., 44
capucina var. mesolepta Rab., 45
construens (Ehr.) Grun., 45
harrisonii (Wm. Sm.) Grun., 45
linearis Cstr., 45
parasitica (Wm. Sm.), 45
undata Wm. Sm., 44
virescens Ralfs, 44

Frustulia, 77
_acuminata_ Kuetz., 76
interposita (Lewis) De Toni, 78
lewisiana (Grev.) De Toni, 77
rhomboides (Ehr.) De Toni, 77
var. amphipleuroides Grun., 77
var. saxonica Rab., 77
vulgaris (Thwaites) De Toni, 77

Gaillonella, 16
_crenulata_ Ehr., 15
_granulata_ Ehr., 15
_moniliformis_ Bail., 16
nummuloides (Dillw.) Bory., 16
_sulcata_ Ehr., 15

_Gloeonema_, 63
_triangulum_ Ehr., 63

Gomphoneis, 70
herculaneum (Ehr.) Cl., 70
mamilla (Ehr.) Cl., 70

Gomphonema, 70
acuminatum, 71
var. coronata (Ehr.) Cl., 71
var. trigonocephala (Ehr.) Cl., 71
var. turris (Ehr.) Cl., 71
var. turris (Ehr.) Cl.?, 71
æquale Greg., 72
angustatum Kuetz., 72
augur Ehr., 72
brasiliense var. demeraræ Grun.?, 73
capitatum Ehr., 72
capitatum var. herculaneum Ehr., 70
constrictum Ehr., 72
geminatum Lyng., 71
_insigne_ Greg., 71
intricatum Kuetz., 72
lanceolatum var. insignis (Greg.) Cl., 71
montanum Schum., 71
olivaceum Lyng., 73
parvulum var. micropus (Kuetz.) Cl., 73
sarcophagus Greg., 72
sphærophorum Ehr., 72
_subclavatum_ var. _montana_ Schum., 71
_tinctum_ Ag., 40
ventricosum Greg., 73

Grammatophora, 36
angulosa var. hamulifera (Kuetz.) Grun., 37
islandica Ehr., 37
marina (Lyng.) Kuetz., 37
var. subtilissima (Bail.) V. H., 37
serpentina Ralfs, 37
_subtilissima_ Bail., 37

Gyrosigma, 75
acuminatum (Kuetz.) Cl., 76
_attenuatum_ (Kuetz.) Cl., 75
balticum (Ehr.) Cl., 75
var. _similis_ (Grun.) Cl., 76
fasciola (Ehr.) Cl., 77
hippocampus (Ehr.), 75
kuetzingii (Grun.) Cl., 76
parkeri var. stauroneioides Grun., 75
prolongatum (Wm. Sm.) Cl., 76
scalproides (Rab.) Cl., 76
simile (Grun.), 76
spencerii var. nodifera Grun., 76
strigilis (Wm. Sm.) Cl., 76

Hantzschia, 113
amphioxys (Ehr.) Grun., 113
var. major Grun., 114
marina (Donk.) Grun., 114
virgata (Roper) Grun., 114

_Himantidium_
_pectinate_ Kuetz., 52

Homoeocladia, 123
filiformis Wm. Sm., 123

Hyalodiscus, 17
radiatus var. arctica Grun., 17
scoticus (Kuetz.) Grun., 18
stelliger Bail., 17
subtilis Bail., 18

Licmophora, 38
baileyi (Ehr.) Grun., 40
ehrenbergii (Kuetz.) Grun., 40
flabellata (Carm.) Ag., 39
gracilis (Ehr.) Grun., 39
var. elongata (Kuetz.) De Toni, 39
lyngbyei (Kuetz.) Grun., 40
ovulum Mer., 39
paradoxa (Lyng.) Ag., 39
_splendida_ Wm. Sm., 39
tincta (Ag.) Grun., 40

Lysigonium, 16
moniliforme (Muell.) Link, 16
_nummuloides_ (Lyng.) O'Meara, 17
varians (Ag.) De Toni, 17

Mastogloia, 86
angulata Lewis, 87
apiculata Wm. Sm., 87
_braunii_ Grun., 87
elegans Lewis, 87
exigua Lewis, 87
kinsmanii Lewis, 87
lanceolata Thwaites, 87
smithii Thwaites, 87

Meloseira, 14
_borreri_ Grev., 17
crenulata (Ehr.) Kuetz., 15
distans (Ehr.) Kuetz., 14
_gowenii_ A. S., 15
granulata (Ehr.) Ralfs, 15
_nivalis_ Wm. Sm., 14
_nummuloides_ Ag., 16
roeseana Rab., 15
var. epidendron (Ehr.) Grun., 15
sulcata Kuetz., 15
undulata (Ehr.) Kuetz., 15
_varians_ Ag., 17

Meridion, 40
circulare (Grev.) Ag., 40
_constrictum_ Ralfs, 41

_Micromega_
_ramosissimum_ Ag., 95

Navicula, 89
_affinis_ Ehr., 83
americana Ehr., 98
_amphibola_ Cl., 92
_amphigomphus_ Ehr., 83
anglica Ralfs, 96
_angulata_ Quek., 74
ardua Mann, 96
_arenaria_ Donk., 95
atomus Nægeli, 100
bacillum Ehr., 98
_baltica_ Ehr., 75
brasiliensis var. bicuneata Cl., forma
constricta, 92
crucigera (Wm. Sm.) Cl., 100
cryptocephala Kuetz., 97
cuspidata Kuetz., 100
var. ambigua (Ehr.) Cl., 100
cyprinus (Wm. Sm.), 95
delawarensis Grun., 92
dicephala Wm. Sm., 96
_digito-radiata_ var. _cyprinus_ (Ehr.?) Wm.
Sm., 95
elegans Wm. Sm., 101
var. cuspidata Cl., 101
_firma_ Kuetz., 84
_fischeri_ A. S., 90
_follis_ Ehr., 80
fuchsii Pant., 91
gastrum Ehr., 96
_gigas_ A. S., 103
_globiceps_ Lagerstedt, 96
gracilis var. schizonemoides (Ehr.) V. H., 95
grevillei (Ag.) Cl., 99
hasta Pant., 97
var. punctata n. var., 97
hennedyi Wm. Sm., 93
var. circumsecta Grun., 93
var. manta A. S., 93
_hippocampus_ Ehr., 75
_hitchcockii_ Ehr., 84
humerosa Bréb., 91
var. _elongata_ Pant., 91
var. _fuchsii_ (Pant.) Cl., 91
humilis Donk., 96
_hungarica_ var. _capitata_ (Ehr.) Cl., 96
inflexa Greg., 96
integra Wm. Sm., 99
_interposita_ Lewis, 78
_iridis_ Ehr., 84
irrorata Grev., 93
lacustris Greg., 92
lanceolata var. arenaria (Donk.) Cl., 95
latissima Greg., 90
var. elongata (Pant.) Cl., 91
libellus Greg., 99
_limosa_ Donk., 81
longa (Greg.) Ralfs, 97
lyra Ehr., 93
var. dilatata A. S., 93
var. ehrenbergii Cl., 93
var.?, 93
maculata (Bail.) Cl., 90
_marginata_ Lewis, 78
_marina_ Ralfs, 92
minima Grun., 98
_mormonorum_ Grun., 107
mutica Kuetz., 97
oblonga Kuetz., 97
_oculata_ Bréb., 86
palpebralis Bréb., 101
pennata A. S., 96
peregrina Ehr., 94
pinnata Pant.?, 96
placenta Ehr., 94
prætexta Ehr., 92
_producta_ Wm. Sm., 83
punctata var. asymmetrica Lagerstedt, 92
punctulata Wm. Sm., 92
pupula var. bacillarioides Grun., 98
pusilla Wm. Sm., 91
var. subcapitata n. var., 91
pygmæa Kuetz., 94
radiosa Kuetz., 94
ramosissima (Ag.) Cl., 95
_rectangulata_ Greg., 110
reinhardtii Grun., 95
rhyncocephala Kuetz., 97
salinarum Grun., 95
semen Ehr., 98
_silicula_ Ehr., 81
_socialis_ Palmer, 104
spectabilis var. emarginata Cl., 94
_sphærophora_ Kuetz., 80
spicula (Hickie) Cl., 100
_trochus_ Kuetz., 80
tumida (Bréb.) Cl., 99
viridula var. rostellata Kuetz., 95
yarrensis Grun., 101

Neidium, 83
affine (Ehr.) Pfitzer, 83
var. amphirhyncus (Ehr.) Cl., 83
var. genuina forma maxima Cl., 83
var. genuina forma minor Cl., 83
amphigomphus (Ehr.) Pfitzer, 83
hitchcockii (Ehr.) Cl., 84
iridis (Ehr.) Cl., 84
productum (Wm. Sm.) Cl., 83

Nitzschia, 114
acicularis (Kuetz.) Wm. Sm., 123
acuminata (Wm. Sm.) Grun., 117
amphibis Grun., 122
amphioxys Wm. Sm., 114
apiculata (Greg.) Grun., 117
bilobata Wm. Sm., 118
circumsuta (Bail.) Grun., 118
clausii Hantzsch, 121
communis Rab., 122
compressa Bail., 116
var. minor H. L. S., 116
_curvula_ Wm. Sm., 121
dissipata (Kuetz.) Grun., 120
dubia Wm. Sm., 118
epithemioides Grun., 118
fluminensis Grun., 120
granulata Grun., 116
insignis Greg., 119
intermedia Hantzsch, 122
linearis (Ag.) Wm. Sm., 122
litoralis var. delawarensis Grun., 118
longissima (Bréb.) Ralfs, 123
forma parva V. H., 123
macilenta Greg., 120
navicularis (Bréb.) Grun., 116
obtusa Wm. Sm., 121
var. flexella H. L. S., 121
var. scalpelliformis Grun., 121
palea (Kuetz.) Wm. Sm., 122
panduriformis Greg., 117
var. minor Grun., 117
_paradoxa_ (Gmelin) Grun., 119
paxillifer (O. F. Mueller) Heib., 119
plana Wm. Sm., 117
_punctata_ (Wm. Sm.) Grun., 116
reversa Wm. Sm., 123
scalaris (Ehr.) Wm. Sm., 119
sigma (Kuetz.) Wm. Sm., 121
var. _curvula_ (Wm. Sm.) De Toni, 121
sigmatella Greg., 121
_sinuata_ var. _tabellaria_ (Grun.) V. H., 119
spathulata Bréb., 120
spectabilis var. americana Grun., 122
tabellaria Grun., 119
tryblionella Hantzsch, 116
vermicularis (Kuetz.) Hantzsch, 120

_Odontidium_
_parasiticum_ Wm. Sm., 45
_tabellaria_ Wm. Sm., 45

Opephora, 43
pacifica (Grun.) Petit, 43
pinnata var. lanceolata n. var., 44
schwartzii (Grun.) Petit, 43

_Orthosira_
_orichalcea_ Wm. Sm., 15
_punctata_ Wm. Sm., 15
_spinosa_ Grev., 15

_Paralia_
_marina_ Heib., 15
_sulcata_ (Ehr.) Cl., 15

Pinnularia, 101
acrosphæria (Bréb.) Cl., 108
var. turgidula Grun.?, 108
æstuarii Cl., 105
appendiculata (Ag.) Cl., 106
blandita n. sp., 108
borealis Ehr., 109
var. scalaris (Ehr.) Cl., 109
braunii Grun., 106
brébissonii (Kuetz.) Cl., 107
cardinaliculus Cl., 107
_cyprinus_ Wm. Sm., 95
dactylus Ehr., 103
var. dariana (A. S.) Cl., 103
var. demeraræ Cl., 103
divergens var. elliptica Grun., 107
gentilis (Donk.) Cl., 103
gibba (Kuetz.) V. H., 109
_interrupta_ forma _stauroneiformis_ Cl., 106
lata (Bréb.) Wm. Sm., 109
legumen Ehr., 107
var.?, 107
leptosoma Grun., 105
major (Kuetz.) Wm. Sm., 102
var. pulchella n. var., 102
mesogongyla (Ehr.) Cl., 109
mesolepta Ehr., 105
var. stauroneiformis Grun., 105
microstauron (Ehr.) Cl., 106
molaris (Grun.) Cl., 105
mormonorum Grun., 107
nobilis Ehr., 103
nodosa forma capitata Cl., 108
parva (Ehr.) Cl., 108
_permagna_ Bail., 82
polyonca (Bréb.) Lewis, 108
rectangulata (Greg.) Cl., 110
socialis (Palmer), 104
stauroptera (Grun.) Cl., 110
var. interrupta forma stauroneiformis Cl., 110
stomatophora (Grun.) Cl., 109
subcapitata Greg., 105
var. paucistriata Grun., 106
tabellaria (Ehr.) Cl., 110
termes (Ehr.) A. S., 106
var. stauroneiformis V. H., 106
trigonocephala Cl., 103
viridis Nitzsch, 104
var. caudata n. var., 104
var. fallax Cl., 104
var.?, 104

Plagiogramma, 42
obesum Grev., 43
pygmæum Grev., 43
tessellatum Grev., 43
wallichianum Grev., 43

Pleurosigma, 73
æstuarii Bréb., 74
_affine_ var. _fossilis_ Grun., 74
angulatum (Quekett) Cl., 74
_balticum_ (Ehr.) Wm. Sm., 75
formosum Wm. Sm., 73
_hippocampus_ (Ehr.) Wm. Sm., 75
naviculaceum Bréb., 74
_normanii_ var. _fossilis_ Grun., 74
obscurum Wm. Sm., 74
rigidum Wm. Sm., 75
_simile_ Grun., 76
_spencerii_ var. _acutiuscula_ Grun., 76
var. _kuetzingii_ Grun., 76
strigosum Wm. Sm., 74
virginiacum H. L. S., 74

Podocystis, 128
adriatica Kuetz., 129
_americana_ Bail., 129

_Podosira_
_hormoides_ Wm. Sm., 18
_maculata_ Wm. Sm., 17

_Podosphenia_
_baileyi_ (Edw.) Lewis, 40
_ehrenbergii_ Kuetz., 40
_lyngbyei_ Kuetz., 40

Polymyxus, 25
coronalis L. W. Bail., 25

Pseudauliscus, 29
radiatus (Bail.) Rattr., 29
spinosus (Christian) Rattr., 29

Pyxidicula, 19
_compressa_ Bail., 116
var. _minor_ H. L. S., 116
cruciata Ehr., 19
_radiata_ O'Meara, 17

Rhabdonema, 35
adriaticum Kuetz., 36
arcuatum (Lyng.) Kuetz., 35
minutum Kuetz., 36

Rhaphoneis, 46
amphiceros Ehr., 46
var. rhombica Grun., 46
belgica var. intermedia Grun., 46

_Rhipidophora_
_elongata_ Kuetz., 39
_paradoxa_ Kuetz., 39

Rhoicosphenia, 56
curvata (Kuetz.) Grun., 56

Rhopalodia, 112
gibba (Kuetz.) Mueller, 112
ventricosa (Kuetz.) Mueller, 113

_Schizonema_
_cruciger_ Wm. Sm., 100
_dillwynii_ Wm. Sm., 78
_grevillei_ Ag., 99
_smithii_ Kuetz., 95

_Scoliopleura_
_tumida_ (Bréb.) V. H., 99

Scoliotropis, 69
latestriata var. amphora Cl., 69

Stauroneis, 88
acuta Wm. Sm., 89
americana A. S., 89
anceps Ehr., 88
var. amphicephala (Kuetz.) Cl., 88
var. gracilis (Ehr.) Cl., 88
crucicula (Grun.) Cl., 89
_exilis_ Kuetz., 59
frickei var. angusta n. var., 88
legumen Ehr., 89
_maculata_ Bail., 90
phoenicenteron Ehr., 88
salina Wm. Sm., 89
smithii Grun., 89
_spicula_ Hickie, 100

_Staurosira_
_construens_ Ehr., 45

Stephanopyxis, 18
_appendiculata_ Ehr., 18
corona (Ehr.) Grun., 18
turris (Grev.) Ralfs, 18

Striatella, 37
interrupta (Ehr.) Heib., 38
unipunctata (Lyng.) Ag., 38

Surirella, 124
amphioxys Wm. Sm., 124
anceps Lewis, 128
angusta Kuetz., 127
arctissima A. S., 128
_bifrons_ Ehr., 124
biseriata (Ehr.) Bréb., 124
_cardinalis_ Kitton, 126
_circumsuta_ Bail., 118
cruciata A. S., 127
crumena Bréb., 126
_davidsonii_ A. S., 126
delicatissima Lewis, 128
_diaphana_ Bleisch, 125
elegans Ehr., 125
fastuosa Ehr., 127
febigerii Lewis, 128
gemma Ehr., 125
gracilis Grun., 127
guatimalensis Ehr., 126
intermedia Lewis, 128
linearis Wm. Sm., 124
_moelleriana_ Grun., 124
oblonga Ehr.?, 127
ovalis Bréb., 126
var. _pinnata_ (Wm. Sm.) De Toni, 126
panduriformis Wm. Sm., 126
pinnata Wm. Sm., 126
var. minuta Grun., 126
recedens A. S., 127
robusta Ehr., 124
splendida (Ehr.) Kuetz., 125
striatula Turpin, 125
tenera Greg., 125

Synedra, 47
acus Kuetz., 48
affinis Kuetz., 50
var. parva (Kuetz.) V. H., 50
var. tabulata (Ag.) V. H., 50
biceps (Kuetz.) A. S., 48
capitata Ehr., 48
danica Kuetz., 48
fulgens (Grev.) Wm. Sm., 50
goulardi Bréb., 48
_gracilis_ Kuetz., 50
oxyrhynchus var. undulata Grun., 48
pulchella (Ralfs) Kuetz., 48
var. abnormis Macchiati?, 48
var. flexella n. var., 49
radians Kuetz., 49
ulna (Nitzsch) Ehr., 47
vaucheriæ var. parvula (Kuetz.) Rab., 49

Tabellaria, 36
fenestrata (Lyng.), 36
flocculosa (Roth) Kuetz., 36

Terpsinoë, 34
americana (Bail.) Ralfs, 34
novæ-cæsareæ Boyer, 34

_Tessella_
_interrupta_ Ehr., 38

Trachyneis, 79
aspera var. intermedia Grun., 79

Trachysphenia, 47
australis Petit, 47

_Triceratium_
_alternans_ Bail., 33
_favus_ Ehr., 31
_obtusum_ Br., 33
_pileotus_ Ehr., 30
_punctatum_ Br., 33
_sculptum_ Shad., 33

Trinacria, 30
pileolus (Ehr.) Grun., 30

_Tripodiscus_
_argus_ Ehr., 26

Tropidoneis, 68
lepidoptera (Greg.) Cl., 69

_Tryblionella_
_punctata_ Wm. Sm., 116
_scutellum_ Wm. Sm., 118

_Vibrio_
_paxillifer_ O. F. Mueller, 119

PLATES

PLATE 1

MELOSEIRA

3-4 Meloseira roeseana var. epidendron (Ehr.) Grun. 15

5-6 Meloseira roeseana Rab. 15

8-9 Meloseira distans (Ehr.) Kuetz. 14

10 Meloseira granulata (Ehr.) Ralfs 15

11-12 Meloseira sulcata Kuetz. 15

15-16-17 Meloseira undulata (Ehr.) Kuetz. 15

GAILLONELLA

13-14 Gaillonella nummuloides (Dillw.) Bory 16

LYSIGONIUM

7 Lysigonium moniliforme (Muell.) Link. 16

18-19 Lysigonium varians (Ag.) De Toni 17

HYALODISCUS

20 Hyalodiscus scoticus (Kuetz.) Grun. 18

21 Hyalodiscus radiatus var. arctica Grun. 17

22 Hyalodiscus stelliger Bail. 17

NOTE.--The figures in all of the plates, except when otherwise
noted, are magnified 800 diameters.

PLATE 2

STEPHANOPYXIS

1-2 Stephanopyxis turris (Grev.) Ralfs 18

3 Stephanopyxis corona (Ehr.) Grun. 18

CYCLOTELLA

4 Cyclotella meneghiniana var. stelligera Cl. and Grun. 20

5-6 Cyclotella operculata (Ag.) Kuetz. 20

7 Cyclotella comta (Ehr.) Kuetz. 20

8 Cyclotella meneghiniana Kuetz. 19

9 Cyclotella striata (Kuetz.) Grun. 19

10 Cyclotella stylorum (Br.?) V. H. 20

11 Cyclotella antiqua Wm. Sm. 20

12 Cyclotella meneghiniana var. stellulifera Cl. and Grun. 20

COSCINODISCUS

13 Coscinodiscus denarius A. S. 22

14 Coscinodiscus excentricus Ehr. 21

15-17 Coscinodiscus subtilis Ehr. 21

16 Coscinodiscus asteromphalus Ehr. 23

18 Coscinodiscus nitidus Greg. 21

19 Coscinodiscus nitidulus Grun. 21

20 Coscinodiscus excentricus var. perpusilla Grun. ? 21

PLATE 3

COSCINODISCUS--Continued

1-11 Coscinodiscus radiatus Ehr. 23

2 Coscinodiscus velatus Ehr. 22

3 Coscinodiscus biangulatus A. S. 23

4 Coscinodiscus subaulacodiscoidalis Rattr. 23

5 Coscinodiscus lewisianus Grev. 24

7 Coscinodiscus argus Ehr. 23

8 Coscinodiscus lineatus Ehr. 21

9 Coscinodiscus marginatus Ehr. 22

10 Coscinodiscus oculus-iridis Ehr. 23

ACTINOCYCLUS

6 Actinocyclus ellipticus var. delawarensis n. var. 27

PLATE 4

ACTINOPTYCHUS

1-4-6 Actinoptychus undulatus (Kuetz.) Ralfs. 24

2 Actinoptychus undulatus (inner stratum) 24

3 Actinoptychus heliopelta Grun. var.? 25

5 Actinoptychus vulgaris var. interrupta n. var. 24

POLYMYXUS

7 Polymyxus coronalis L. W. Bail. 25

AULACODISCUS

8 Aulacodiscus argus (Ehr.) A. S. 26

PLATE 5

EUODIA

1 Euodia gibba Bail. 34

POLYMYXUS

2 Polymyxus coronalis L. W. Bail., zone view 25

EUPODISCUS

3 Eupodiscus radiatus Bail. 28

AULISCUS

4 Auliscus cælatus Bail. 29

5 Auliscus sculptus (Wm. Sm.) Ralfs 29

6 Auliscus punctatus Bail. 28

7 Auliscus (intermediate form between A. cælatus and A.
sculptus) 29

8 Auliscus pruinosus Bail. 28

PSEUDAULISCUS

9 Pseudauliscus radiatus (Bail.) Rattr. 29

10 Pseudauliscus spinosus (Christian) Rattr. 29

PLATE 6

ACTINOCYCLUS

1 Actinocyclus barkleyi var. aggregata Rattr. 27

2 Actinocyclus moniliformis Ralfs. 27

BIDDULPHIA

3 Biddulphia antediluviana (Ehr.) V. H. 32

5 Biddulphia reticulum (Ehr.) 33

6 Biddulphia favus (Ehr.) V. H. 31

7-8 Biddulphia alternans (Bail.) V. H. 33

TRINACRIA

9 Trinacria pileolus (Ehr.) Grun. 30

DITYLUM

4 Ditylum intricatum (West) Grun. 30

TERPSINOË

10 Terpsinoë americana (Bail.) Ralfs. 34

11 Terpsinoë novæ-cæsareæ Boyer 34

PLATE 7

BIDDULPHIA

1-2-3-4 Biddulphia biddulphiana (Smith) 31

5 Biddulphia rhombus (Ehr.) Wm. Sm. 32

6 Biddulphia granulata Roper 32

7 Biddulphia turgida (Ehr.) Wm. Sm. 32

8 Biddulphia smithii (Ralfs) V. H. 32

9 Biddulphia lævis Ehr. 33

10 Biddulphia lævis Ehr. Sporangial frustules (260 diam.) 33

EUNOTOGRAMMA

11 Eunotogramma læve Grun. 33

PLATE 8

RHABDONEMA

1-2-3 Rhabdonema arcuatum (Lyng.) Kuetz. 35

4-5-6 Rhabdonema adriaticum Kuetz. 36

7 Rhabdonema minutum Kuetz. 36

TABELLARIA

8-9-10 Tabellaria flocculosa (Roth) Kuetz. 36

11-12 Tabellaria fenestrata (Lyng.) Kuetz. 36

GRAMMATOPHORA

13-14 Grammatophora marina var. subtilissima (Bail.) V. H. 37

15-16 Grammatophora angulosa var. hamulifera (Kuetz.) Grun. 37

17-18 Grammatophora marina (Lyng.) Kuetz. 37

19-20 Grammatophora islandica Ehr. 37

21 Grammatophora serpentina Ralfs. 37

STRIATELLA

22-23 Striatella unipunctata (Lyng.) Ag. 38

24 Striatella interrupta (Ehr.) Heib. 38

ATTHEYA

25 Attheya decora West 38

PLATE 9

LICMOPHORA

1-2 Licmophora flabellata (Carm.) Ag. 39

3-4 Licmophora lyngbyei Kuetz. 40

5 Licmophora ehrenbergii (Kuetz.) Grun. 40

6-7 Licmophora paradoxa (Lyng.) Ag. 39

8-9 Licmophora ovulum Mer. 39

10 Licmophora baileyi (Edw.) Grun. 40

11 Licmophora gracilis (Ehr.) Grun. 39

12-13 Licmophora gracilis var. elongata (Kuetz.) De Toni 39

14-15 Licmophora tincta (Ag.) Grun. 40

PLATE 10

MERIDION

1-2-3 Meridion circulare (Grev.) Ag. 40

DIATOMA

4 Diatoma vulgare var. grande (Wm. Sm.) Grun. 42

5-6 Diatoma anceps (Ehr.) Kirchn. 42

7-8 Diatoma hiemale (Lyng.) Heib. 42

9-10 Diatoma vulgare Bory. 42

PLAGIOGRAMMA

11 Plagiogramma tessellatum Grev. 43

12 Plagiogramma obesum Grev. 43

13 Plagiogramma pygmæum Grev. 43

14 Plagiogramma wallichianum Grev. 43

EUNOTOGRAMMA

15 Eunotogramma læve Grun. 33

OPEPHORA

16-19 Opephora schwartzii (Grun.) Petit. 43

17 Opephora pinnata var. lanceolata n. var. 44

18 Opephora pacifica (Grun.) Petit. 43

FRAGILARIA

20-21 Fragilaria virescens Ralfs. 44

22-23 Fragilaria arctica Grun. 44

24-25-27-28-29 Fragilaria undata Wm. Sm. 44

26 Fragilaria undata Wm. Sm., var.? 44

30 Fragilaria construens (Ehr.) Grun. 45

31 Fragilaria harrisonii (Wm. Sm.) Grun. 45

34 Fragilaria capucina var. mesolepta Rab. 45

35 Fragilaria parasitica (Wm. Sm.) 45

36 Fragilaria sp. ? 45

37 Fragilaria linearis Cstr. 45

RHAPHONEIS

38 Rhaphoneis amphiceros Ehr. 46

39-40 Rhaphoneis amphiceros var. rhombica Grun. 46

41 Rhaphoneis belgica var. intermedia Grun. 46

SYNEDRA

32-33 Synedra radians Kuetz. 49

PLATE 11

SYNEDRA--Continued

1-5-6 Synedra ulna (Nitzsch) Ehr. Sporangial 47

2 Synedra danica Kuetz. 48

3 Synedra biceps (Kuetz.) A. S. 48

4-7-11 Synedra ulna (Nitzsch) Ehr. 47

8 Synedra capitata Ehr. 48

9-18 Synedra acus Kuetz. 48

10 Synedra fulgens (Grev.) Wm. Sm. 50

12-13 Synedra goulardi Bréb. 48

14-15-16 Synedra pulchella (Ralfs) Kuetz. 48

17 Synedra pulchella var. abnormis Macchiati? 48

PLATE 12

SYNEDRA--Continued

1 Synedra oxyrhynchus var. undulata Grun. 48

2 Synedra pulchella var. flexella n. var. 49

3 Synedra affinis Kuetz. 50

4 Synedra affinis var. tabulata (Ag.) V. H. 50

5-6 Synedra vaucheriæ var. parvula (Kuetz.) Rab. 49

7 Synedra affinis var. parva (Kuetz.) V. H. 50

8 Synedra radians (Kuetz.) H. L. S. 49

DIMEROGRAMMA

9-10 Dimerogramma marinum (Greg.) 46

11 Dimerogramma surirella (Ehr.) Grun. 46

12-13-14 Dimerogramma minus (Greg.) Ralfs. 47

TRACHYSPHENIA

15 Trachysphenia australis Petit. 47

ACTINELLA

16-17-18 Actinella punctata Lewis. 54

ASTERIONELLA

19-20-21 Asterionella formosa Hass. 50

22 Asterionella inflata Heib. 50

EUNOTIA

23 Eunotia hemicyclus (Ehr.) Ralfs 53

24-25 Eunotia lunaris (Ehr.) Grun. 53

PLATE 13

EUNOTIA--Continued

1-2 Eunotia major (Wm. Sm.) Rab. 51

3 Eunotia gracilis (Ehr.) Rab. 51

4 Eunotia major (Wm. Sm.) Rab. (intermediate form) 51

5 Eunotia prærupta Ehr. 53

6-7 Eunotia pectinalis (Kuetz.) 52

8-10 Eunotia pectinalis var. undulata Ralfs 52

9 Eunotia pectinalis var. solierolii (Kuetz.) 52

11 Eunotia luna Ehr. var.? 52

12 Eunotia pectinalis var. ventricosa Grun. 52

13 Eunotia robusta Ralfs (E. scalaris Ehr.) 53

14 Eunotia robusta Ralfs (E. prioritis Ehr.) 53

15 Eunotia robusta Ralfs (E. decadon Ehr.) 53

16 Eunotia robusta Ralfs (E. octodon Ehr.) 53

17-22 Eunotia robusta Ralfs (E. heptodon Ehr.) 53

18 Eunotia bactriana Ehr. 54

19 Eunotia prærupta var. bidens Grun. 53

20 Eunotia bidentula Wm. Sm. 54

21 Eunotia robusta Ralfs (E. diadema Ehr.) 53

23 Eunotia prærupta Ehr. var.? 53

24 Eunotia robusta Ralfs (E. triodon Ehr.) 53

25 Eunotia robusta Ralfs (E. tetraodon Ehr.) 53

26 Eunotia formica Ehr. var.? 54

27 Eunotia biceps Ehr. 53

28-29 Eunotia sp.? 54

30-31 Eunotia veneris Kuetz. 52

32 Eunotia nymanniana Grun. 51

PLATE 14

AMPHIPRORA

1-2 Amphiprora pulchra Bail. 68

3 Amphiprora alata Kuetz. 68

4 Amphiprora conspicua Grev. 68

5 Amphiprora paludosa Wm. Sm. 68

6-7 Amphiprora ornata Bail. 68

TROPIDONEIS

8-9 Tropidoneis lepidoptera (Greg.) Cleve. 69

SCOLIOTROPIS

10-11 Scoliotropis latestriata var. amphora Cleve. 69

PLATE 15

AMPHORA

1 Amphora robusta Greg. 65

3 Amphora crassa Greg. 65

4 Amphora obtusa Greg. 67

5-6-19 Amphora proteus Greg. 65

7 Amphora ovalis (Bréb.) Kuetz. 65

8-18 Amphora coffæiformis (Ag.) Kuetz. 66

9-10 Amphora lineolata Ehr. 66

11 Amphora areolata Grun. 66

12-21 Amphora ostrearia Bréb. 66

13 Amphora lævis Greg. 66

14-15 Amphora ocellata var. cingulata Cleve. 67

16 Amphora angusta var. culensteinii Grun. 67

17 Amphora arenaria Donk. 67

20 Amphora acuta Greg. 66

AURICULA

2 Auricula mucronata (H. L. Smith) Peragallo 69

PLATE 16

ACHNANTHES

1-2 Achnanthes longipes Ag. 58

3 Achnanthes brevipes Ag. 59

4-5-6 Achnanthes subsessilis Kuetz. 59

7-8 Achnanthes inflata (Kuetz.) Grun. 59

9 Achnanthes coarctata (Bréb.) Grun. 59

10-11-12 Achnanthes lanceolata (Bréb.) Grun. 59

13 Achnanthes danica (Floegel) Grun. (lower valve) 60

14-15 Achnanthes exigua Grun. 59

16-17 Achnanthes linearis forma curta H. L. Smith 59

COCCONEIS

18 Cocconeis scutellum var.? 57

19-20 Cocconeis placentula Ehr. 57

21 Cocconeis scutellum Ehr. (upper valve) 57

22 Cocconeis dirupta Greg. (lower valve) 58

23-24 Cocconeis pediculus Ehr. 57

25-26 Cocconeis pellucida Grun. 58

27-28 Cocconeis scutellum var. ornata Grun. 57

29 Cocconeis placentula var. lineata (Ehr.) V. H. 58

ANORTHONEIS

30-31 Anorthoneis excentrica (Donk.) Grun. 56

PLATE 17

FRUSTULIA

1 Frustulia lewisiana (Grev.) De Toni 77

2 Frustulia rhomboides (Ehr.) De Toni 77

3 Frustulia rhomboides var. amphipleuroides Grun. 77

4 Frustulia vulgaris (Thwaites) De Toni 77

5 Frustulia interposita (Lewis) De Toni 78

6 Frustulia rhomboides var. saxonica (Rab.) De Toni 77

BREBISSONIA

7 Brébissonia boeckii (Kuetz.) Grun. 79

8 Brébissonia palmerii n. sp. 80

AMPHIPLEURA

9 Amphipleura pellucida Kuetz. 78

10-11 Amphipleura rutilans (Trentepohl) Cl. 78

ANOMOEONEIS

12 Anomoeoneis serians (Bréb.) Cl. 80

13 Anomoeoneis serians forma minor 80

14 Anomoeoneis follis (Ehr.) Cl. 80

TRACHYNEIS

15 Trachyneis aspera var. intermedia Grun. 70

MASTOGLOIA

16 Mastogloia kinsmanii Lewis 87

17 Mastogloia angulata Lewis 87

18 Mastogloia lanceolata Thwaites 87

19 Mastogloia smithii Thwaites 87

20 Mastogloia elegans Lewis 87

21-22-23 Mastogloia apiculata Wm. Sm. 87

24 Mastogloia exigua Lewis 87

PLATE 18

CYMBELLA

1 Cymbella aspera (Ehr.) Cl. 61

2 Cymbella cymbiformis (Kuetz.) Bréb. 62

3 Cymbella cistula (Hempr.) Kirchn. 62

4 Cymbella lanceolata (Ehr.) Kirchn. 62

5 Cymbella mexicana (Ehr.) A. S. 62

6 Cymbella naviculiformis Auerswald. 60

7 Cymbella tumida (Bréb.) V. H. 62

8 Cymbella philadelphica n. sp. 63

9 Cymbella ehrenbergii Kuetz. 60

10 Cymbella heteropleura (Ehr.) Kuetz. 60

11 Cymbella rhomboidea n. sp. 63

12 Cymbella turgida (Greg.) Cl. var.? 63

13 Cymbella sinuata Greg. 61

14 Cymbella ventricosa Kuetz. 62

15-19 Cymbella excisa (Kuetz.) De Toni. 61

16 Cymbella amphicephala Nægeli. 61

17 Cymbella cuspidata Kuetz. 60

18 Cymbella affinis Kuetz. 61

20 Cymbella gracilis (Rab.) Cl. 64

21 Cymbella prostrata (Berk.) Cl. 63

22 Cymbella ventricosa Kuetz.? 62

23 Cymbella turgida (Greg.) Cl. 63

24 Cymbella triangulum (Ehr.) Cl. 63

25 Cymbella lacustris (Ag.) Cl. 64

PLATE 19

GOMPHONEIS

1 Gomphoneis mamilla (Ehr.) Cl. 70

2 Gomphoneis herculaneum (Ehr.) Cl. 70

GOMPHONEMA

3 Gomphonema montanum Schum. 71

4 Gomphonema geminatum Lyng. 71

5 Gomphonema acuminatum var. turris (Ehr.) Cl. 71

6-12 Gomphonema lanceolatum var. insignis (Greg.) Cl. 71

7 Gomphonema acuminatum var. coronata (Ehr.) Cl. 71

8 Gomphonema constrictum Ehr. 72

9-10 Gomphonema sphærophorum Ehr. 72

11 Gomphonema acuminatum var. turris (Ehr.) Cl.? 71

13 Gomphonema ventricosum Greg. 73

14 Gomphonema intricatum Kuetz. 72

15 Gomphonema æquale Greg. 72

16 Gomphonema sarcophagus Greg. 72

17 Gomphonema parvulum var. micropus (Kuetz.) Cl. 73

18-19 Gomphonema angustatum Kuetz. 72

20 Gomphonema acuminatum var. trigonocephala (Ehr.) Cl. 71

21 Gomphonema augur Ehr. 72

22 Gomphonema capitatum Ehr. 72

23 Gomphonema olivaceum Lyng. 73

24 Gomphonema brasiliense var. demeraræ Grun.? 73

RHOICOSPHENIA

25-26-27 Rhoicosphenia curvata (Kuetz.) Grun. 56

PLATE 20

DICTYONEIS

1 Dictyoneis marginata var. maxima n. var. 79

2 Dictyoneis marginata var. commutata Cleve. 79

3 Dictyoneis marginata var. typica Cleve. 78

DIPLONEIS

4 Diploneis crabro var. pandura (Bréb.) Cl. 85

6 Diploneis campylodiscus (Grun.) Cl. 86

7-8 Diploneis gruendleri (A. S.) Cl. 85

9 Diploneis crabro Ehr. var.? 85

10 Diploneis excentrica n. sp. 85

11 Diploneis fusca var. delicata (A. S.) Cl. 85

12 Diploneis puella (Schum.) Cl. 85

13 Diploneis crabro var. pandurella Cl.? 85

14 Diploneis elliptica (Kuetz.) Cl. 84

15 Diploneis crabro var. expleta (A. S.) Cl. 85

16 Diploneis geminata (Grev.) Cl. 86

17 Diploneis smithii (Bréb.) Cl. 84

NAVICULA

5 Navicula lyra Ehr. var.? 93

PLATE 21

CALONEIS

1 Caloneis permagna (Bail.) Cl. 82

2 Caloneis permagna var. lewisiana n. var. 82

3 Caloneis silicula (Ehr.) Cl. 81

4 Caloneis silicula var. inflata (Grun.) Cl. 81

5 Caloneis brevis var. vexans (Grun.) Cl. 82

6-7 Caloneis wardii Cl. 82

8 Caloneis trinodis (Lewis) 81

9 Caloneis trinodis (Lewis) var.? 81

10 Caloneis powellii (Lewis) Cl. 83

18 Caloneis formosa (Greg.) Cl. 82

NEIDIUM

11 Neidium affine (Ehr.) Pfitzer 83

12 Neidium affine var. genuina forma minor Cl. 83

13 Neidium affine var. amphirhyncus (Ehr.) Cl. 83

14 Neidium amphigomphus (Ehr.) Pfitzer. 83

15 Neidium hitchcockii (Ehr.) Cl. 84

16 Neidium productum (Wm. Sm.) Cl. 83

17 Neidium iridus (Ehr.) Cl. 84

PLATE 22

PLEUROSIGMA

1 Pleurosigma strigosum Wm. Sm. 74

2 Pleurosigma rigidum Wm. Sm. 75

3 Pleurosigma angulatum (Quekett) Cl. 74

4 Pleurosigma obscurum Wm. Sm. 74

5 Pleurosigma formosum Wm. Sm. 73

6 Pleurosigma naviculaceum Bréb. 74

7 Pleurosigma æstuarii Bréb. 74

8 Pleurosigma virginiacum H. L. Smith 74

PLATE 23

GYROSIGMA

1 Gyrosigma strigilis (Wm. Sm.) Cl. 76

2 Gyrosigma balticum (Ehr.) Cl. 75

3 Gyrosigma hippocampus (Ehr.) 75

4 Gyrosigma simile (Grun.) 76

5 Gyrosigma acuminatum (Kuetz.) Cl. 76

6 Gyrosigma scalproides (Rab.) Cl. 76

7 Gyrosigma parkeri var. stauroneioides Grun. 75

8 Gyrosigma spencerii var. nodifera Grun. 76

9 Gyrosigma fasciola (Ehr.) Cl. 77

PLATE 24

NAVICULA

1 Navicula maculata (Bail.) Cl. 90

2 Navicula prætexta Ehr. 92

3 Navicula latissima Greg. 90

4 Navicula irrorata Grev. 93

5 Navicula latissima var. elongata (Pant.) Cl. 91

6 Navicula fuchsii Pant. 91

PLATE 25

NAVICULA

1 Navicula tumida (Bréb.) Cl. 99

2 Navicula brasiliensis var. bicuneata Cl. forma
constricta. 92

3 Navicula delawarensis Grun. 92

4-6 Navicula pusilla Wm. Sm. 91

5 Navicula humerosa Bréb. 91

7 Navicula spectabilis var. emarginata Cl. 94

8 Navicula pusilla var. subcapitata n. var. 91

9 Navicula punctulata Wm. Sm. 92

10 Navicula lyra Ehr. 93

11 Navicula hennedyi var. manca A. S. 93

12 Navicula hennedyi Wm. Sm. 93

13 Navicula lyra var. dilatata A. S. 93

14 Navicula yarrensis Grun. 101

15 Navicula yarrensis Grun. (smaller form) 101

16 Navicula yarrensis Grun. var.? 101

PLATE 26

NAVICULA

1-2 Navicula cuspidata Kuetz. 100

3 Navicula cuspidata var. ambigua (Ehr.) Cl. 100

4 Navicula spicula (Hickie) Cl. 100

5 Navicula integra Wm. Sm. 99

6 Navicula mutica Kuetz. 97

8 Navicula americana Ehr. 98

9 Navicula pupula var. bacillarioides Grun. 98

10 Navicula bacillum Ehr. 98

11 Navicula semen Ehr. 98

12 Navicula atomus Nægeli. 100

13 Navicula minima Grun. 98

14 Navicula ramosissima (Ag.) Cl. 95

15 Navicula crucigera (Wm. Sm.) Cl. 100

16 Navicula viridula var. rostellata Kuetz. 95

17 Navicula radiosa Kuetz. 94

19 Navicula gracilis var. schizonemoides (Ehr.) V. H. 95

20 Navicula peregrina Ehr. 94

21 Navicula cyprinus (Wm. Sm.) 95

22 Navicula reinhardtii Grun. 95

23 Navicula lanceolata var. arenaria (Donk.) Cl. 95

24 Navicula salinarum Grun. 95

25 Navicula gastrum Ehr. 96

26 Navicula anglica Ralfs. 96

DIPLONEIS

7 Diploneis oculata (Bréb.) Cl. 86

STAURONEIS

18 Stauroneis frickei var. angusta n. var. 88

PLATE 27

STAURONEIS--Continued

1 Stauroneis phoenicenteron Ehr. 88

2 Stauroneis acuta Wm. Sm. 89

3 Stauroneis americana A. S. 89

4 Stauroneis anceps var.? 88

5 Stauroneis anceps var. gracilis (Ehr.) Cl. 88

6 Stauroneis salina Wm. Sm. 89

7 Stauroneis anceps var. amphicephala (Kuetz.) Cl. 88

8 Stauroneis anceps var.? 88

9 Stauroneis anceps var.? 88

10 Stauroneis crucicula (Grun.) Cl. 89

11 Stauroneis smithii Grun. 89

NAVICULA

12 Navicula lacustris Greg. 92

13 Navicula hasta Pant. 97

14 Navicula hasta var. punctata n. var. 97

15 Navicula punctata var. asymmetrica Lagerstedt 92

16 Navicula dicephala Wm. Sm. 96

17 Navicula placenta Ehr. 94

18-19 Navicula inflexa Greg. 96

20 Navicula pinnata Pant.? 96

21 Navicula oblonga Kuetz. 97

22 Navicula pennata A. S. 96

23 Navicula pygmæa Kuetz. 94

24 Navicula humilis Donk. 96

PLATE 28

PINNULARIA

1 Pinnularia nobilis Ehr. 103

2 Pinnularia major var. pulchella n. var. 102

3 Pinnularia dactylus Ehr. 103

4 Pinnularia major (Kuetz.) Wm. Sm. 102

PLATE 29

PINNULARIA--Continued

1 Pinnularia gentilis (Donk.) Cl. 103

2 Pinnularia viridis Nitzsch. 104

3 Pinnularia dactylus var. dariana (A. S.) Cl. 103

4 Pinnularia viridis var. fallax Cl. 104

5 Pinnularia socialis Palmer 104

6 Pinnularia æstuarii Cl. 105

7 Pinnularia rectangulata (Greg.) Cl. 110

8 Pinnularia trigonocephala Cl. 103

9 Pinnularia major (Kuetz.) Wm. Sm. (small form near P.
viridis) 102

10 Pinnularia dactylus var. demeraræ Cl. 103

11 Pinnularia mormonorum (Grun.) 107

12 Pinnularia brébissonii (Kuetz.) Cl. 107

13 Pinnularia mesolepta Ehr. 105

14 Pinnularia termes var. stauroneiformis V. H. 106

15 Pinnularia molaris (Grun.) Cl. 105

16 Pinnularia braunii Grun. 106

17 Pinnularia termes (Ehr.) A. S. 106

18 Pinnularia appendiculata (Ag.) Cl. 106

19 Pinnularia microstauron (Ehr.) Cl. var.? 106

20 Pinnularia subcapitata Greg. 105

PLATE 30

PINNULARIA--Continued

1 Pinnularia cardinaliculus Cl. 107

2 Pinnularia viridis var. fallax Cl.? (var. B., Wm.
Sm.?). 104

3 Pinnularia legumen Ehr. 107

4 Pinnularia legumen var.? 107

5 Pinnularia gibba (Kuetz.) V. H. 109

6 Pinnularia mesogongyla (Ehr.) Cl. 109

7 Pinnularia acrosphæria (Bréb.) Cl. 108

8 Pinnularia acrosphæria var. turgidula Grun. 108

9 Pinnularia tabellaria (Ehr.) Cl. var.? 110

10 Pinnularia leptosoma Grun. 105

11 Pinnularia stauroptera var. interrupta Cl. 110

12 Pinnularia stomatophora (Grun.) Cl. 109

13 Pinnularia stauroptera (Grun.) Cl. 110

14 Pinnularia parva (Ehr.) Cl. var.? 108

15-19 Pinnularia nodosa forma capitata Cl. 108

16 Pinnularia subcapitata var. paucistriata Grun. 105

17 Pinnularia viridis Nitzsch var. 104

18 Pinnularia viridis var. caudata n. var. 104

20 Pinnularia mesolepta var. stauroneiformis Grun. 105

21 Pinnularia polyonca (Bréb.) Lewis. 108

22 Pinnularia borealis Ehr. 109

23 Pinnularia lata (Bréb.) Wm. Sm. 109

24 Pinnularia borealis var. scalaris (Ehr.) Cl. 109

25 Pinnularia blandita n. sp. 108

PLATE 31

NAVICULA

1 Navicula elegans Wm. Sm. 101

2 Navicula elegans var. cuspidata Cl. 101

3-4 Navicula grevillei (Ag.) Cl. 99

5 Navicula libellus Greg. 99

6-7 Navicula palpebralis Bréb. 101

8 Navicula rhyncocephala Kuetz. 97

9 Navicula cryptocephala Kuetz. 97

10 Navicula longa (Greg.) Ralfs. 97

PINNULARIA

11 Pinnularia brébissonii (Kuetz.) Cl. 107

12 Pinnularia borealis Ehr. 109

13 Pinnularia divergens var. elliptica Grun. 107

EPITHEMIA

14 Epithemia turgida (Ehr.) Kuetz. 111

15-21 Epithemia argus Kuetz. 111

16 Epithemia argus var.? 111

17 Epithemia muelleri A. S. 111

18 Epithemia zebra var. proboscidea (Kuetz.) Grun. 112

19 Epithemia gibberula var. producta Grun. 112

20 Epithemia musculus Kuetz. 112

22 Epithemia musculus var. constricta (Bréb.) V. H. 112

RHOPALODIA

23 Rhopalodia gibba (Kuetz.) Mueller 112

24 Rhopalodia ventricosa (Kuetz.) Mueller 113

PLATE 32

NITZSCHIA

1 Nitzschia circumsuta (Bail.) Grun. 118

2 Nitzschia plana Wm. Sm. 117

3 Nitzschia granulata Grun. 116

4 Nitzschia navicularis (Bréb.) Grun. 116

5 Nitzschia panduriformis var. minor Grun. 117

6 Nitzschia apiculata (Greg.) Grun. 117

7 Nitzschia tabellaria Grun. 119

8 Nitzschia tryblionella Hantzsch 116

10-11 Nitzschia bilobata Wm. Sm. 118

12 Nitzschia litoralis var. delawarensis Grun. 118

13 Nitzschia acuminata (Wm. Sm.) Grun. 117

14-25 Nitzschia amphibia Grun. 122

15 Nitzschia palea (Kuetz.) Wm. Sm. 122

16 Nitzschia fluminensis Grun. 120

17 Nitzschia obtusa var. scalpelliformis Grun. 121

18 Nitzschia linearis (Ag.) Wm. Sm. 122

19 Nitzschia communis Rab. 122

20 Nitzschia clausii Hantzsch. 121

21 Nitzschia epithemioides Grun. 118

24 Nitzschia vermicularis (Kuetz.) Wm. Sm. 120

HANTZSCHIA

9 Hantzschia amphioxys (Ehr.) Grun. 113

22 Hantzschia marina (Donk.) Grun. 114

23 Hantzschia virgata (Roper) Grun. 114

PLATE 33

NITZSCHIA

1 Nitzschia longissima (Bréb.) Ralfs 123

2 Nitzschia intermedia Hantzsch 122

3 Nitzschia spectabilis var. americana Grun. 122

4-5 Nitzschia sigmatella Greg. 121

6 Nitzschia scalaris (Ehr.) Wm. Sm. 119

7 Nitzschia macilenta Greg. 120

8 Nitzschia insignis Greg. 119

9 Nitzschia vermicularis (Kuetz.) Hantzsch 120

10 Nitzschia longissima forma parva V. H. 123

11 Nitzschia reversa Wm. Sm. 123

12 Nitzschia acicularis (Kuetz.) Wm. Sm. 123

13-14 Nitzschia paxillifer (O. F. Mueller) Heib. 119

HOMOEOCLADIA

15 Homoeocladia filiformis Wm. Sm. 123

PLATE 34

SURIRELLA

1 Surirella striatula Turpin 125

2 Surirella anceps Lewis 128

3 Surirella intermedia Lewis 128

4 Surirella arctissima A. S. 128

5-6 Surirella delicatissima Lewis 128

7 Surirella intermedia Lewis forma minor? 128

CYMATOPLEURA

8-9 Cymatopleura solea (Bréb.) Wm. Sm. 129

PLATE 35

SURIRELLA

1 Surirella fastuosa Ehr. 127

2 Surirella biseriata (Ehr.) Bréb. 124

3 Surirella splendida (Ehr.) Kuetz. 125

4 Surirella crumena Bréb. 126

5 Surirella ovalis Bréb. 126

6 Surirella tenera Greg. 125

7 Surirella recedens A. S. 127

8 Surirella linearis Wm. Sm. 124

9 Surirella oblonga Ehr.? 127

10 Surirella cruciata A. S. 127

11 Surirella gracilis Grun. 127

12-13 Surirella amphioxys Wm. Sm. 124

PLATE 36

SURIRELLA--Continued

1 Surirella elegans Ehr. 125

2 Surirella robusta Ehr. 124

3 Surirella febigerii Lewis 128

4 Surirella gemma Ehr. 125

5 Surirella guatimalensis Ehr. 126

6 Surirella panduriformis Wm. Sm. 126

7-9 Surirella pinnata Wm. Sm. 126

8 Surirella angusta Kuetz. 127

PLATE 37

CYMATOPLEURA

1 Cymatopleura elliptica (Bréb.) Wm. Sm. 129

2 Cymatopleura elliptica forma spiralis 129

3-4 Cymatopleura marina Lewis 129

CAMPYLODISCUS

5 Campylodiscus hibernicus Ehr. 130

6 Campylodiscus echeneis Ehr. 130

PLATE 38

1 Amphora gigantea var. fusca A. S. 65

2 Meloseira crenulata (Ehr.) Kuetz. 15

3-4 Licmophora baileyi (Edw.) Grun. 40

5 Coscinodiscus polyacanthus Grun. 22

6-7 Ditylum intricatum (West) Grun. 30

8 Pyxidicula cruciata Ehr. 19

9 Gyrosigma scalproides (Rab.) Cl. 76

10 Coscinodiscus asteromphalus var. omphalantha (Ehr.)
Grun. 23

11 Rhabdonema minutum Kuetz. 36

12 Gyrosigma kuetzingii (Grun.) Cl. 76

13 Gyrosigma prolongatum (Wm. Sm.) Cl. 76

14 Cymbella parva (Wm. Sm.) Cl. 61

15 Gomphoneis herculaneum (Ehr.) Cl. (zone view) 70

16 Cymbella ventricosa Kuetz. 62

17-18 Eunotia sp. (abnormal?) 54

PLATE 39

1 Nitzschia spectabilis var. americana Grun. (zone view) 122

2 Nitzschia panduriformis Greg. 117

3 Hantzschia amphioxys (Ehr.) Grun. 113

4 Hantzschia amphioxys var. major Grun. 114

5 Nitzschia dubia Wm. Sm. 118

6 Nitzschia amphioxys Wm. Sm. 114

7 Nitzschia compressa (Bail.) 116

8 Nitzschia compressa var. minor H. L. Smith 116

9 Surirella intermedia Lewis (zone view) 128

10 Surirella arctissima A. S. forma minor 128

11 Surirella ovalis Bréb. 126

12 Surirella biseriata (Ehr.) Bréb. 124

13 Nitzschia sigma (Kuetz.) Wm. Sm. 121

14 Nitzschia obtusa var. flexella H. L. Smith 121

15 Stauroneis legumen Ehr. 89

16 Nitzschia obtusa Wm. Sm. 121

PLATE 40

1 Caloneis liber (Wm. Sm.) Cl. 81

2 Anomoeoneis sphærophora (Kuetz.) Cl. 80

3 Nitzschia spathulata Bréb. 120

4 Stauroneis ? abnormal 89

5 Navicula ? abnormal 101

6 Podocystis adriatica Kuetz. 129

7 Nitzschia dissipata (Kuetz.) Grun. 120

8 Cymbella ventricosa Kuetz. (zone view) 62

9 Navicula radiosa Kuetz. (zone view) 94

10 Detail of Rhabdonema arcuatum (Lyng.) Kuetz. 35

11 Diatoma anceps (Ehr.) Kirchn. (containing
chromataphores) 42

12 Coscinodiscus asteromphalus Ehr. (trans. section, after
Pelletan) 23

13-14-15 Transverse section (diagram) of Pinnularia showing
straight, oblique and grooved raphes 101

16 Transverse section (diagram) of Biddulphia favus
showing inner punctate stratum (after Deby) 31

17 Transverse (ideal) section of Surirella 124

18-19 Transverse (ideal) section of Pinnularia, before and
after division 101

20 Transverse section of Nitzschia linearis (Ag.) Wm. Sm. 122

21 Transverse section (diagram) of Navicula 89

22 Transverse section (diagram) of Cymbella 60

23 Transverse section (diagram) of Amphora 65