Chapter XIV: Part II: Marine Invertebrates (9)

^D. arborescens.^ This species is about one inch long and variable
in color, but is usually reddish-brown or rose. There are no
tentacles, but in their place are two antler-like appendages
pointing forward and branched like a tree. All along the back are
two rows of these curiously branched processes, which give to
the animal the appearance of a plant. These /cerata/, or dorsal
papillae, are delicately transparent, contractile, and richly
colored. The function of these papillae is not fully known. As
the animal has no specialized breathing-organs, it is reasonable
to suppose that respiration is carried on through the outer skin
and perhaps all over the surface of these branched papillae. The
liver, which [pg354] in most nudibranchs is extremely large and
completely surrounds the stomach, in /Dendronotus/ also extends
into these dorsal cerata, so that they may have some sort of
digestive function.

GENUS ^AEolis^

^AE. papillosa.^ This is probably the commonest nudibranch upon
the North Atlantic coast, and it occurs as frequently in European
waters. It may readily be found clinging to stones, algae, the
piling of wharves, eel-grass, etc., in bays or in rocky tide-pools.
The color is yellowish-gray to orange, with purplish or olive
spots. The cerata are very numerous, and cover the dorsal portion
of the animal save for an open space along the middle of the back.
There are two sets of tentacles, the two dorsal and the two simple
labial tentacles. The foot tapers behind to a sharp point, and is
truncate in front. As in /Dendronotus/, the liver is diffused into
the cerata, which in /AEolis/ are simple tubular processes without
the branching character of those of the former. Both species lay
their eggs in a gelatinous, bobbin-like cord, which is hung in
festoons over rocks or upon zooephytes, or at times they wind the
cord in a coil upon the surfaces of stones. When the young first
hatch out, they are provided with a glassy nautiloid shell, a fact
which would indicate that at some remote period they were, like
most mollusks, provided with a shell. /AEolis/ swims in an inverted
position, and is at times exceedingly active. It is very variable
in coloring and in the number of cerata.

GENUS ^Doris^

^D. bilamellata.^ In /Doris/ we find a quite different type of
nudibranch from that presented by the two genera /Dendronotus/
and /AEolis/. In one there were numerous branched cerata or dorsal
papillae, in the other many plain cerata, and in neither case were
there any specialized [pg355] breathing-organs. In /Doris/,
however, there are no dorsal papillae at all, the back being covered
with calcareous spicules, which form a sort of secondary shell.
There is a circlet, or rosette, of retractile plume-like gills, or
branchiae, placed in the middle of the back posteriorly. There are
various species of /Doris/, and of closely allied genera belonging
to the family /Dorididae/, which are to be found along the New
England coast in tide-pools and among rocks. Those seen by the
writer never appeared to be other than very sluggish creatures, and
proved to be rather unsatisfactory tenants of the aquarium.

When discovered at low tide upon moist seaweed or stones, or when disturbed in the water, nudibranchs often appear like small lumps of jelly-like tissue, without a single attractive feature. It is only when they are placed in a jar of sea-water and left unmolested for a few moments that they unfold their beauties to the view. On the Pacific coast there are numerous species of nudibranchs, occupying corresponding shore stations and exhibiting the same degree of high coloration. There are over a thousand species of sea-slugs scattered about the various seas. They find their greatest development in tropical waters, and for brilliancy of tint and variation in form are unequaled by any other class of animal life, save perhaps the butterflies.

ORDER =PROSOBRANCHIATA=

To this exceedingly large and comprehensive order of gasteropods belong the great majority of univalve mollusks. In point of number of genera and species and in abundance of individuals, the prosobranchs probably exceed all the other orders of mollusks combined. They may be called the typical gasteropods, the shell being univalvular and generally spiral, and the animal exhibiting the singular torsion of the visceral mass which has placed the breathing-organs forward of the heart. They are provided with an operculum (placed upon the posterior dorsal portion of the foot), which is used to close the aperture of the shell against [pg356] enemies when the animal retires within its fortress. They are all marine except a very few families, which, supposedly of marine derivation, have become terrestrial in habit.

The prosobranchs are further subdivided into suborders according to certain peculiarities of the heart and breathing-organs. There is a group of these prosobranchs which gives evidence of an inferior degree of that visceral torsion which is always found in the gasteropods. In this group, or suborder, the heart has two auricles, and there is a pair of gills instead of only a single one. Other internal organs are paired just as they were represented to be in the schematic mollusk. This group also seems to show its primitive character in the want of a proboscis and a siphon, or, in some families, by having the ventricle of the heart traversed by the intestinal canal, just as in the lower class of mollusks, which includes the clams and oysters. For the most part the shells of this group are not typically spiral, but are patelliform, shield-like coverings, with only a suggestion of a spiral form at the very tip of the apex. This group of primitive prosobranchs is included in the following suborder:

SUBORDER ~DIATOCARDIA~

This suborder is named from the presence of two auricles in the heart.

FAMILY ~ACMAEIDAE~

The first family to be noted is the /Acmaeidae/. Its principal genus, /Acmaea/, is well represented on both the east and the west coast of the United States.

GENUS ^Acmaea^

^A. testudinalis.^ This species is found in vast numbers all along
the New England shore, clinging to the rocks between tides. They
are usually called limpets. The shell is solid, conical, with an
oval outline, and with no trace of a spiral form in the adult. When
the shell is thoroughly cleaned, it generally presents a mottled
coloration of pale green, brown, and white. Inside it is white
and nacreous, with a large brown [pg357] area under the apex.
The animal has a powerful foot, by means of which it is enabled
to cling to a rock with great strength. In order to dislodge it,
it is necessary to approach carefully, and, taking the creature
unawares, quickly slip a broad knife-blade under the foot,
otherwise it is quite impossible to tear it from its resting-place.
/A. testudinalis/ lives entirely between tides, and ranges from the
northernmost waters to New York. It feeds upon algae and is a very
sluggish animal. It has been said to leave its resting-place and
wander about in search of food, returning to its original and usual
spot when the tide begins to ebb. (Page 343.)

^A. testudinalis,^ variety ^alveus.^ This variety is smaller, more
fragile, and oblong. It lives upon eel-grass, its oblong shell
being adapted to the narrow leaves of the grass. The coloration is
brighter--reddish-brown spots on a white surface. It is exceedingly
common on the New England coast.

^A. mitra.^ On the Pacific coast there are a number of acmaeas. /A.
mitra/ is often found dead upon the beaches. It is conical in form
and pure creamy-white in color. It looks very much like a clown's
pointed cap.

^A. patina.^ This is also very abundant in California. Outside it
is dark in color and is often incrusted with mineral deposits.
Within there is a dark ring around the edge, then a zone of
bluish-white, and a patch of brown just beneath the apex.

GENUS ^Lottia^

^L. gigantea.^ This is the largest of the California limpets.
Specimens three inches long have been found. The outer surface
of the shell is rough and brownish in color. The apex is near
one end. Within it is almost black, shining, lustrous, with a
horseshoe-shaped muscle-scar under the apex. The color is bluish
and brown. (Plate LXV.)

FAMILY ~FISSURELLIDAE~

This is an extensive family, including several genera and a number
of species, commonly known as keyhole-limpets. In the general form
of the shell they closely resemble the true limpets, the /Acmaeidae/,
except that they have a hole, or rather a slit, in the shell just
back of the apex. Often this slit is so long that it has entirely
removed the apex of the conical shell.

GENUS ^Fissurella^

^F. alternata^, ^F. barbadensis^. These species occur upon the
southern shores of the United States, the latter, however, being
confined to [pg358] extreme southern Florida. /F. barbadensis/
has heavy longitudinal ribs and is light green within, with a rosy
circle about the apical perforation. (Plate LXV.)

GENUS ^Glyphis^

^G. aspersa.^ One of the numerous species belonging to this family
which are found on the west coast of the United States. It is about
one and a half inches long, grayish-white, with sharply raised
longitudinal ridges, slightly rayed, crossed by revolving ribs,
which give to the outer surface a decussated appearance. The apex
is forward of the center, and is entirely replaced by a round
perforation. The edge is wrinkled, and within smooth and white.

GENUS ^Lucapina^

^L. crenulata.^ The largest of the keyhole-limpets; the shell
is often four inches in length, while the animal, with its huge
yellowish foot and dark-colored mantle, which is thrown back,
almost concealing the shell upon its back, is much larger. The
apical perforation is very large. Shell flattened, with radiating,
rounded, crowded ribs; brownish-white in color; edge crenulated;
within pure white. It is found at Monterey, but live specimens are
not very frequently seen near the beach. (Plate LXVI.)

FAMILY ~HALIOTIDAE~

GENUS ^Haliotis^

This family is closely allied to the /Fissurellidae/. The species are known on the Pacific coast by the name of abalone shells, and in England and the Channel Islands as ormers or sea-ears. There are no species of /Haliotis/ on the east coast of the United States, but one has recently been dredged at a considerable depth in West Indian waters. This family, with the last, possesses the striking anatomical feature of having the heart traversed by the digestive tract. It also has two gills, the degree of torsion in the visceral mass not being sufficient to have crowded out and destroyed the original right gill. The shell is spiral, but is so greatly flattened, and the body-whorl is so greatly extended, that the shell quite loses the spiral appearance. Along the dorsal side of the shell is a row of holes, through which project numerous tentacular processes from the mantle. The outer surface of the shell, before it is polished, is usually rough and unattractive, but within, when the [pg359] animal is removed, it displays a most beautiful and highly colored nacreous surface. The spot near the center of the inner shell surface where the muscles of the foot were attached is usually most brilliantly colored. The shell of the abalone is susceptible of taking a very high degree of polish, and is extensively used in commerce for colored mother-of-pearl and for inlaid work. /Haliotis/ is a vegetable-feeding genus. They cling with great tenacity to rocks about low tide, and it requires skill to remove them without breaking the shell. There are several species in California. The Chinese use the abalone for food, and have waged a persistent war upon the family along the Pacific coast until the specimens are not nearly as common as formerly. They are also eaten in France and in Japan.

^H. splendens.^ The largest and perhaps the most attractive in
appearance of the Californian species. Speaking of this beautiful
shell, Professor Keep says: "Within, a whole rainbow is condensed
in one of the magnificent shells, though the shades of green are
most conspicuous. The coloring in the center is particularly fine,
resembling a peacock's tail. There are about six open holes near
one side of the shell, and its length is about the same number of
inches." (Plate LXVI.)

^H. rufescens.^ A large abalone, which sometimes attains a length
of eight or nine inches. It is red in color, with three open holes
in the body-whorl. The outer portion of the shell is usually
incrusted with mineral deposit and overgrown with vegetation.

^H. cracherodii.^ Very dark green without, with five to nine holes;
length from one to six inches; spire exceedingly short. Common on
the Californian coast in crevices of rocks at low tide.

FAMILY ~TROCHIDAE~

This is one of the largest and most interesting families of the /Mollusca/. It contains many apparently widely separated genera and a host of species, which for the most part are littoral, the majority actually living between tide-marks. The typical trochid shell is top-shaped or pyramidal, having a broad base and many closely wound flat whorls terminating in a sharp apex. All the trochids are nacreous within the aperture--a character which is constant throughout the family. The animal has but one gill (the left), a short snout, and often frontal lobes on the head. The edge of the mantle or the epipodial line of the foot is usually ornamented with from three to five cirri. The tentacles are [pg360] long and slender, with short peduncles for the eyes; the operculum is corneous, with a central nucleus. The animals are herbivorous, feeding upon algae. The trochids are essentially tropical shells, and the most of the genera which are comprised in the family are only to be encountered in the warm waters of the Pacific and Indian oceans. Some forms are very beautiful, and frequently are used as mantel ornaments, and the shells of one little species, which is opalescent in its coloring, are still extensively gathered in the East Indies, to be polished and strung like pearls in necklaces.

GENUS ^Margarita^

On the Atlantic coast north of Cape Cod the trochids are represented by the genus /Margarita/, with five or six species. The shells are small, thin, and globosely depressed, with smooth or transversely striated whorls. The aperture is nearly circular, with a simple lip.

^M. cinerea.^ This species has several prominent revolving ridges
upon the upper side of the whorls, with finer ones on the base.
Very fine growth-lines cover the entire shell. It ranges all along
the coast north of Cape Cod, but is not usually found between
tides. The writer has dredged many specimens in shallow water at
Eastport and Bar Harbor.

^M. helicina.^ A thinner and more globose species than the last,
with a translucent, shining, smooth surface of a yellowish or olive
color. /M. helicina/ is very fond of the leaves of /Laminaria/, and
is often found clinging to them when storms have torn these great
algae from the bottom and cast them upon the shore. At Bar Harbor
they are common upon the eel-grass in Rodicks Weir. This species
can generally be distinguished by its iridescent, metallic luster.

^M. undulata.^ A commoner species, perhaps, than either of the
preceding, sometimes found on the rocks of sheltered coves at
exceptionally low tides. Judging from the number often to be found
in the stomachs of fishes, they must be considered excellent food
by the cod and its allied species which thrive along the Maine
coast. No doubt millions of /M. undulata/ are yearly destroyed
in this way. The shell is depressed, with four rounded whorls, a
flattish base, and a large umbilical opening. In color it varies
from rose-red to brown. The surface is decorated with numerous
revolving raised lines placed at uniform distances. Just below
the suture the body-whorl is somewhat undulated with short folds.
Height three tenths of an inch, base four tenths of an inch.
[pg361]

GENUS ^Calliostoma^

This genus is better represented on the Pacific coast of the United States than upon the Atlantic. It comprises a series of marvelously beautiful shells, often exquisitely colored. They are regularly conical or pyramidal in shape, with flattened bases. One never tires in the search for calliostomas. They are not common enough to cause one to lose interest, and whenever a good specimen is captured it seems as though one had found some gem cut and polished by nature's skilful hand and prepared for a place of honor in the cabinet.

^C. occidentale.^ The only species of this genus found on the
northeast coast. It is larger than /Margarita cinerea/, but
somewhat resembles it. It is shining nacreous within and without,
and has strong revolving ribs, the upper one on each whorl often
being broken into a circular row of white dots. The lip is
crenulated. This very pretty species is not likely to be met with
upon the shore, but may be dredged in shallow water on gravelly
bottoms along the Maine coast. Height about one half of an inch.

^C. jujubinum.^ A species which occurs in the waters of Florida.
Its form is almost that of a true pyramid. The sutures can scarcely
be distinguished. The shell is marked by brown and purplish-red
spots on a white background, and has numerous revolving ribs broken
into rows of white dots like little glazed beads. The umbilicus
is funnel-shaped and wide. In Tampa Bay this shell is frequently
found on sponges, and may sometimes be gathered on the beach after
storms, even as far north as Hatteras. There are as many as twenty
species of this genus in American Atlantic waters, but they are
either rare or have deep-water stations.

^C. annulatum.^ A remarkable species of /Calliostoma/, found in
California. The whorls are adorned with revolving rows of raised
dots, and the sutures are frescoed in exquisite purple. This
beautiful species lives upon seaweed, and on pleasant days comes
to the surface of the water. It can then be collected from a boat
by drawing in quantities of seaweed. It is very unlikely that the
collector will ever find a specimen upon the beach, for the shell
is too fragile to withstand the rough handling of the waves. Length
one inch.

^C. canaliculatum.^ The largest member of this genus to be found
in American waters. It resembles the last species in form, but
lacks the purple sutures. The revolving ribs are very numerous and
prominent. There is no umbilicus. Length one to one and a half
inches. Found on the Pacific coast.

^C. costatum.^ A heavier shell than the preceding, with somewhat
more rounded whorls. Reddish-brown in color; numerous revolving
ridges; no umbilicus; about three quarters of an inch in length. It
is found in rocky places, and sometimes in considerable numbers,
just at low-tide mark. Found in California. [pg362]

GENUS ^Chlorostoma^

This genus is represented in California by several species, the commonest of which is probably /C. funebrale/--a doleful name, no doubt given on account of the jet-black color.

^C. funebrale.^ The shell is thick and strong, like most
between-tide species, which are constantly exposed to the buffeting
of the waves. It is to be found in countless thousands upon rocks
exposed at low tide, and may be gathered at any time except full
flood-tide, like the littorinas and purpuras of the east coast.
Within the aperture the surface is nacreous and greenish in tint;
the last whorl is drawn in, like gathers, at the suture. The
umbilicus is closed. There is a white nodule at the base of the lip
of the columella. Length one half of an inch to one inch. (Plate
LXVII.)

^C. brunneum.^ This species is brown, as its name would indicate,
and there is greenish nacre within the aperture. It lives upon
kelp, or upon rocks at very low tide. Length about an inch. (Plate
LXVI.)

GENUS ^Trochiscus^

^T. norrisi.^ A flattened shell with rounded, dome-like spire and
obtuse apex; a fairly common species. It has a wide, deep umbilicus
and a sharp lip. It is of a rich brown color, with dark chestnut
about the umbilical region and greenish-white within the umbilicus;
there is a band of dark olive-green about the inner margin of the
lip. The shell is about two inches in diameter and of a somewhat
greater height. The operculum is multispiral, with a central
nucleus, and is shaggy and rough. Like all other trochids, it feeds
upon algae. It is often found upon the beach after violent storms.
Found in California, south of San Francisco. (Plate LXVI.)

GENUS ^Livona^

^L. pica.^ This large and interesting trochid is a West Indian
species which sometimes occurs in Florida. It lives about coral
reefs and rocky shores, attaching itself in vast numbers to the
rocks. This shell is a favorite refuge for large hermit-crabs. It
is a curious sight in certain of the West India islands to see a
/Livona pica/ shell scrambling up a tree, looking very much out of
place upon the back of some terrestrially inclined crustacean. When
well cleaned it is a beautiful shell, with black wavy lines over a
greenish-white nacreous foundation. The animal has a row of waving
cirri upon each side of the mantle, and long, slender tentacles.
It is largely used as an article of diet in the West Indies and
Central America. (Plate LXVII.)

FAMILY ~TURBINIDAE~

This family is very closely allied to the trochids, the most striking difference being in the operculum, which in the /Turbinidae/ is calcareous and usually smooth and very convex on the outside. [pg363] The shells are nacreous within, and the animal, with its rows of waving cirri upon each side, is very suggestive of /Trochus/. They are, for the most part, shallow-water or littoral forms.

GENUS ^Turbo^

^T. castaneus.^ This species has a range as far north as Cape
Hatteras, and is especially abundant at Tampa, on the west coast of
Florida. The peculiar operculum is sufficient to identify the genus
at once. One variety of this species has a crenulated shoulder upon
the body-whorl and is referred to as ^Turbo crenulatus^, A series
of intermediate forms establishes the specific identity of the two
varieties. (Plate LXVII.)

FAMILY ~NERITIDAE~

The /Neritidae/ are strictly littoral forms, almost entirely confined to the warmer waters of tropical seas. The animal preserves the usual diatocardian features--has a short snout and long tentacles. Unlike the trochids and /Turbo/, it has no cirri along the epipodial margin. The shells are peculiarly shaped, the spire being greatly flattened and scarcely noticeable on account of the unduly large development of the body-whorl; thus the shell takes on a decidedly patelliform appearance. It is without an umbilicus. In the principal genus /Nerita/ the outer lip is sharp on the edge, but greatly thickened just within.

GENUS ^Nerita^

^N. peleronta.^ This shell has two teeth on the wide, flat
columellar lip, and about them is a blotch of red, suggesting
blood. The common name of this shell, "bleeding-tooth," is very
appropriate. Found in southern Florida. (Plate LXVII.)

^N. tessellata^ is a smaller species, with heavy revolving ribs,
and is further decorated with transverse oblique black lines. The
operculum is calcareous. Both of these species have the habit of
absorbing the entire inner portion of their shells. They belong
to the West Indian fauna, and occur in great numbers on rocky or
coral shore stations. They also may be found on the east Florida
coast, well to the south. A third species, ^N. versicolor^, often
occurs, associated with the other two. It is somewhat smaller than
the others and can easily be distinguished by the four teeth on
the columellar lip, the edge of the columella being convex. (Plate
LXVII.)

GENUS ^Neritina^

The genus /Neritina/ is very closely allied to the last, having quite the same form of shell; but it is usually more globular and [pg364] variously ornamented by bright spots or zigzag lines of coloration. The neritinas have acquired the habit of ascending rivers, until they have become almost wholly a brackish- or fresh-water genus. The metropolis of this genus is in the South Sea Islands, where it attains a wonderful development in the clear running streams of the volcanic islands.

^N. reclivata.^ A very pretty olive-green species, with very
fine, wavy, longitudinal lines of coloration, found in almost
all Floridian streams above the action of the tide. The nacre of
the columella and within the aperture is bluish-green, and the
operculum is rich olive. (Plate LXVI.)

^N. viridis.^ A small, intensely green species, which, unlike most
neritinas, is strictly marine. It belongs to the great West Indian
faunal province, but is occasionally found upon the shores of
Florida and of Texas.

The prosobranch gasteropods thus far considered (belonging to the suborder /Diatocardia/) all show by their anatomical structure that the process of visceral torsion, though carried very far within them, has not been complete enough to crowd out and finally destroy one of each of the paired organs. Both auricles of the heart (with some exceptions) were left intact.

SUBORDER ~MONOTOCARDIA~

In this the second suborder of the prosobranch gasteropods, the twisting visceral process has been carried to the extreme. The heart has but one auricle. There is but one gill (on the left side), and this is attached to the inner side of the mantle flap. In other respects the presence of certain specialized organs would probably indicate that gasteropods belonging to this suborder are a step higher in the scale of life than those which belong to the /Diatocardia/.

FAMILY ~JANTHINIDAE~

GENUS ^Janthina^

The genus /Janthina/ has an exceedingly thin and semi-transparent shell, deep violet in color on the base and lighter blue on the spire. An interesting feature of this genus is the mode of depositing the ova. The female exudes from a gland in the foot a [pg365] glutinous secretion which hardens in water, and, being filled with air-bubbles, constitutes a float. On the under side of this are deposited the eggs in rows of little capsules. While attached to this float it is impossible for a /Janthina/ to sink, and hence it is that so many of these creatures are sacrificed in onshore gales of wind.

^J. fragilis.^ The shell of this species is so brittle and fragile
that it is very clearly not adapted to a life near shore. It is in
reality a pelagic species which is occasionally blown ashore during
easterly gales along the Atlantic coast of the United States. Vast
numbers of these pretty creatures are sometimes encountered far out
at sea, floating quietly on the surface. When storms drive them
upon the beach, they become utterly helpless; since their foot
is not adapted for crawling upon the sand, they soon perish, and
their brittle shells are demolished by the surf. In Florida the
beaches are sometimes fairly lined with /Janthina/ shells, which
make a band of purple along the high-tide mark as far as the eye
can reach; then it may be years before they again appear. (Plate
LXVIII.)

FAMILY ~SCALIDAE~

GENUS ^Scala^

The shells of /Scala/ have such a peculiar scheme of decoration that once seen they can never be mistaken. They are generally pure white, with well-rounded whorls, all of which are crossed at even distances by greatly elevated and smooth ribs. Each rib represents a rest-period, when the creature thickened the rim of the shell-aperture. The aperture is generally round, with a continuous lip. The animal has a retractile proboscis and long, slender tentacles with eyes at the outer bases, and is a predaceous, [pg366] carnivorous creature. Some Asiatic species of this genus, remarkable for their beauty and rarity, have been greatly prized by collectors. A single specimen of the now well-known ^S. pretiosa^ of China has been sold for two hundred dollars--a fancy price, indeed, for a shell which can now be bought for a dollar! There are over fifty species of /Scala/ on the Atlantic coast, but most of them are either rare or belong to a zone of deeper water; there are, however, four or five species which are exceedingly common.

^S. lineata.^ A species which ranges from Hatteras to New England.
It has about eight whorls, and is slightly brownish in color. The
ribs are robust and not greatly elevated; there are from seventeen
to nineteen on the body-whorl. The shell is sometimes painted with
a few revolving brownish lines.

^S. multistriata.^ The transverse ribs are much smaller but very
numerous; the small spaces between them are marked with many fine
revolving lines. Found from Cape Cod southward.

^S. groenlandica.^ Essentially an arctic species, which has found
its way down to the New England coast. It is readily distinguished
by the flattened, coarsely rounded, revolving ribs, which follow
the volutions of the spire. Over them are the usual transverse
heavy ribs peculiar to this genus.

^S. angulata.^ The whorls touch one another only by the ribs,
of which there are nine to each volution. This species has a
remarkably wide range, occurring from Cape Cod to southern Florida.
(Plate LXVIII.)

These four species vary from one half of an inch to one inch in
length. All of them are found on the beach after storms or may be
dredged in shallow water near the shore.

FAMILY ~NATICIDAE~

This large and interesting family is well represented in the Atlantic waters of the United States, but its more beautiful members live in the tropics. The New England and New Jersey species are dull in color, but offer much of interest to the collector and student. The foot is enormously large, and carries in front a great shield-like fleshy process, which curves back over the head of the animal and serves as a plow in pushing its way through the heavy wet sand of the beach. When the creature is thus seen extended in the act of crawling, one wonders how it is possible for it to withdraw so great an amount of body into its shell; but if it is suddenly seized or irritated, it will quickly [pg367] demonstrate its ability to hide itself completely within its house and to close the door very effectively by means of its operculum. The eyes seem to be wanting, or they are concealed under the skin of the head. The shell is usually quite large, with a depressed spire and well-rounded whorls--especially the body-whorl, which appears to be greatly swollen. The umbilicus is usually open and moderately large, the lip simple.

GENUS ^Polynices^ (^Lunatia^, ^Natica^).

^P. heros^ (generally referred to as ^Lunatia^ or ^Natica
heros^). One of the commonest large shells and one of the most
characteristic species of the New England and New Jersey littoral
fauna. It is exceedingly common along the Long Island shore, where
it may be found on the open beach, in pools with a sandy bottom
left by the receding tide. It is usually partially and frequently
wholly buried in the sand. The umbilicus is open and large, the
operculum corneous, and the shell heavy and ashy-white to brownish,
with (when young) a yellowish epidermis. Its length is from two to
four inches. It has no ornamentation whatever. /P. heros/ is a most
voracious creature and spends its time in hunting for flesh--either
alive or dead--to devour. It feeds upon dead fish, or upon other
mollusks whose shell it is able to pierce by means of its radula,
making a little round hole through which it sucks out the flesh
from within. The curious egg-cases of this species have already
been referred to. (See Plate I.) It glues together particles of
sand into the form of a basin with the bottom knocked out and
broken on one side. In the gelatinous substance of this basin it
deposits its eggs in a regular order. These hatch out in midsummer.
Egg-cases of this kind can always be found wherever /Polynices/
lives. For a long time naturalists were greatly puzzled by these
curious things, and their blunders are recorded in earlier works,
where these egg-cases have been elaborately described as living
animals belonging to various invertebrate orders. The largest and
best specimens of /P. heros/ are to be found south of Cape Cod.
(Page 343.)

^P. triseriata.^ A small shell of exactly the same shape as /P.
heros/, but decorated with three revolving series of bluish or
chestnut spots. It is pretty well determined that this so-called
species is only the young of /P. heros/. It is very abundant all
along the coast.

^P. duplicata.^ This is even more abundant than /P. heros/. It
has a flatter shell, with an obtuse apex and dome-like spire.
The umbilicus is partly or wholly closed by a thick, callous,
shelly process thrown off from the columellar lip, and is chestnut
in color. The surface of the shell is smooth, often polished,
ashy-white below and light chestnut above. The operculum is
corneous. The length of the shell varies in different localities
from one half of an inch to about two [pg368] inches; the breadth
slightly exceeds the length. /P. duplicata/ has a very extensive
range, from the Gulf of Mexico to Newfoundland. The largest and
finest specimens are found in the vicinity of New York and at
Hatteras. In Florida they are usually smaller. This species cannot
be confounded with any other upon our coast on account of the heavy
callous deposit over the umbilicus. Its habits are similar to those
of /P. heros/.

^Natica clausa.^ A Northern species which is fairly abundant on the
Maine coast. It has a shelly operculum, and the umbilicus is neatly
closed by a pure white, shining callosity. Its length is about one
half an inch, its color livid white to light brown, white within.
The calcareous operculum at once determines this shell. This
species (as well as the following one) has retained the generic
name of /Natica/ because of the shelly operculum, as explained
below.

^N. canrena.^ One of the handsomer species of /Natica/, which
occurs in Florida. Sometimes it is seen as far north as Hatteras.
The shell is white, with bars of light chestnut circling the
whorls, and with zigzag lines of darker purplish hue crossing them.
The base of the shell is white. The aperture is large and flaring,
and is purplish within. The umbilicus is partially closed by an
entering callous plug. The operculum is calcareous, with eccentric,
deeply cut grooves. Found in sandy stations just about low-water
mark. (Plate LXVIII.)

^P. lewisii.^ A species which occurs on the west coast of the
United States. It resembles its New England relative /P. heros/
very closely. /P. lewisii/ is a Northern species, and does not
range south of Oregon. Professor Keep mentions one specimen of the
size of a six-inch globe, but such dimensions are very unusual. A
good-sized specimen need not exceed four inches in height.

^P. recluziana.^ A species well known on the southern coast of
California. The umbilicus is closed by a thick, highly polished
white callosity, and the general shape of the shell is strongly
suggestive of the common east-coast species /P. duplicata/. A large
specimen is about two inches in diameter.

[There has been much confusion in the generic nomenclature of
this family. The old name /Natica/ once did service for all the
species; then the names /Lunatia/, /Neverita/, and /Polynices/ were
applied to certain special forms; but it has been wisely proposed
by conchologists to use the name /Natica/ for those forms having
a shelly operculum, and to adopt the name /Polynices/ for those
having a corneous operculum. /Lunatia/ and /Neverita/ have become
subgenera of /Polynices/.] [pg369]

GENUS ^Sigaretus^

A very interesting species of this genus occurs on the east coast, sparingly in New Jersey, but very abundantly south of Hatteras. /Sigaretus/ is a modified /Natica/. The spire is flattened and minute. The body-whorl, being greatly expanded, gives a wide, flaring, oblique aperture. The shell is ear-shaped and white, with fine revolving lines. There is no umbilicus. The operculum is small and rudimentary. The animal is large, with an enormous foot and greatly developed propodium, and is a sand-dweller. The common east-coast form is ^S. perspectivus^. (Plate LXVIII.)

FAMILY ~CAPULIDAE~

GENUS ^Crepidula^

^C. fornicata.^ All collectors of mollusks on the Atlantic coast
sooner or later encounter this exceedingly common species adhering
to oyster-shells or scallops, and often to other large live shells.
It is cast upon the beach along the entire length of the Atlantic
coast. The shell is obliquely oval, dull whitish in color, and
either smooth or rough or even ribbed, according to the nature
of the surface to which it clings. The spire is almost entirely
suppressed, the little inconspicuous apex being turned to one
side and closely pressed down against the body of the shell. When
looking into the interior of the shell one is reminded of a boat,
for the upper portion of the aperture is covered by a horizontal
shelly partition, called the diaphragm, a space being left below
which would correspond to the forecastle of a ship. The "stern" is
round, and the "bow" is suggestively pointed.

^C. plana.^ In this species the shell is white and flat, or
slightly concave. Although it is pointed at the "bow" end and
square at the "stern," the nautical resemblance stops there,
because, being flat, there are no swelling sides and bow. The
diaphragm is about one half the length of the shell, convex,
shining, white, and translucent. /C. plana/ lives generally within
the aperture of large dead shells. It has a wide range, from Maine
to Florida.

^C. aculeata.^ A common Floridian species which has a remarkable
range, being found in nearly all the tropical and semi-tropical
waters of the world. It is smaller than /C. fornicata/, is
reddish-brown with a white diaphragm, and has several radiating
ribs on the back, which are inclined to be nodulous. (Plate
LXVIII.) [pg370]

On the Pacific coast the following species are found: ^C. adunca^,
with a strongly recurved apex, and less than one inch long; ^C.
rugosa^, rough, brown, with the apex lying on the edge of the
shell, and one inch in length; ^C. navicelloides^, almost identical
with the east-coast /C. plana/. /C. aculeata/ also appears.

GENUS ^Crucibulum^

/Crucibulum/ has a peculiar rounded shield-like form, with a very small apex on one side. Within there is a cup-shaped appendage attached by one side to the inner margin of the shell. This latter feature at once determines the genus.

^C. striatum.^ This species has radiating riblets, cut by circular
lines of growth. No dimension would quite reach an inch. It is a
common shell on the Atlantic coast, and will be found adhering
to stones and other shells, but it is not, strictly speaking, a
littoral species.

^C. spinosum.^ The shell exhibits a strong tendency to spinous
processes on its back. Found along the southern part of the
California shore.

FAMILY ~LITTORINIDAE~

GENUS ^Littorina^

/Littorina/ is probably the most characteristic genus of Northern littoral regions. Together with some of its allied genera it is also, probably, equally characteristic of various tropical littoral faunas all over the world. The family comprises strictly between-the-tides genera and species. Indeed, it is suspected that some species of /Littorina/ are making very fair progress toward a terrestrial condition, for they actually live above high-tide mark,--even in the branches of overhanging trees,--and must certainly pass days at a time out of their natural element. That such a transformation is possible need not for a moment be doubted, for there are many land mollusks to-day that give abundant evidence of having been at some past time aquatic or marine species. These changes in nature are constantly going on, and the gradual substitution of a lung for a gill is no very startling metamorphosis. [pg371]

The littorinas fairly swarm in favorable localities upon all shore stations. In Maine and Massachusetts the bold, rocky coast furnishes a home for several species. Often the rocks at low tide are black with them; the algae that cling in wet masses to the exposed rocks are alive with them. One cannot walk about in such localities without crushing hundreds of specimens. Sometimes they will be found clinging in clusters upon the piling of old wharves, or crawling about the bottom at or about the low-tide mark. The best specimens of /Littorina/ are found in stations where they are bathed twice a day by pure, uncontaminated sea-water; those living near the mouths of streams, or where the water is brackish or impure, are usually small and degenerate. They are vegetable feeders, and have received the common name of "periwinkles." In Great Britain they are used among the poorer classes for food. The animal has a short, broad muzzle, and eyes at the outer bases of the tentacles. The foot is longitudinally grooved, and there is a rudimentary siphonal fold in the mantle. The shells are turbinated, usually heavy, few-whorled, and with a round aperture.

^L. litorea.^ This is supposed to be an importation from the Old
World--to have come over by way of Iceland and Greenland, and
then to have migrated down the Labrador coast. For many years
Cape Cod formed a barrier to its advance, but now the species is
abundant at Newport, and is reported at New York. It occurs on
the Maine coast in astonishing numbers, living in vast colonies
on the rocks exposed at low tide. The shell is thick, imperforate
(no umbilicus), and usually has flat, spiral ribs. The columella
is broad and white; the lip thin and black. The general color
varies from black to olive or to dingy gray--sometimes reddish.
The operculum is corneous, with the nucleus near the outer edge.
Despite the variableness of this very common shell (the variations
being chiefly in the height of the spire), it has certain
unmistakable characteristics which, once seen, will enable the
collector to determine it at once.

^L. rudis.^ A smaller species than the last. It is strong
and coarse, with revolving grooves and ribs, or smooth, with
interrupted whitish bands and spots. A very common variety of
this species is much smaller than the typical form, being about
one sixth to one fourth of an inch long, smooth, with white and
yellowish spots on olive. It clings to the rocks near high-tide
mark, and is usually found attached to its resting-place by a
bit of hardened mucus. While the typical /L. rudis/ is heavy and
banded, with a moderately high spire and no color, this [pg372]
variety is thinner, with a higher spire and smoother surface,
and has a color-scheme of decoration. It would be impossible
to disconnect the two, for a large series of specimens will
demonstrate beyond doubt, through every minute degree of variation,
that the two forms belong to one and the same species. The station
of /L. rudis/ is much the same as that of /L. litorea/, but the
smaller colored variety of /rudis/ prefers quieter and more
sheltered spots. It is occasionally found on reeds and grasses,
on the piling of wharves, on large boulders above the line of
algae, and on algae. It has been the writer's experience not to find
/rudis/ and /litorea/ associated together.

^L. palliata.^ A low-spired, globular shell with a large, tumid,
smooth body-whorl. The columella is flattened, curved below, and
imperforate. The color is exceedingly variable, but is usually
bright, shining olive, and this is especially the case with those
individuals that find their station in the dense masses of algae
that form so conspicuous a feature of a low-tide scene on a rocky
New England coast. From pure olive-green to yellow or bright red,
with revolving black bands, seems a long chromatic leap, but it
is not too great for the Designer of these pretty little globular
shells. As a rule, the color of the shell simulates pretty closely
that of the seaweed upon which it lives, and inexperienced eyes
may easily overlook hundreds of specimens, all within close reach.
The banded varieties are less common. The head of the animal is
somewhat orange in color, the foot slate. The distinguishing
features of this species are the smooth, globular shell, the low
spire, the broadly flattened columella, and the orange-colored head
of the animal. It is found on /Fucus/ between tides, and often
associated with /L. rudis/, on the whole coast north of New Jersey.
The three preceding species are distinctly boreal in their range,
but their place is taken in southern Atlantic waters of the United
States by the following exceedingly common species:

^L. irrorata.^ A solid, robust shell, which attains a length of
about one inch. It is in many respects suggestive of /L. litorea/,
its Northern relative, but the spire is higher, with straighter
outlines, and the apex is acute. The surface is ornamented with
closely set, revolving ribs; the sutures are indistinct; the lip
is thin, though thickened just within; and the color is whitish to
pale cinereous greenish, sometimes spotted with broken brownish
lines. Within it is white, with a reddish tinge on the columella,
and brownish spots on the edge of the lip. This species ranges from
Maryland to Texas; its station is between tides.

^L. angulifera.^ As the last species resembles /L. litorea/, so
this other common Southern form resembles a greatly developed and
large /L. rudis/ of the smoother variety. It has a high-spired
shell, with an acute black tip. It has about six whorls, which are
variously decorated by wavy, oblique black lines and revolving
black lines broken into series of dots and larger spots near the
suture. The ground-color varies from yellow to purple. None of
the colors are very vivid. Within it is yellowish-white. This
species has a much thinner and more delicate shell than any of
the littorinas thus far considered. It is common on the piling of
wharves and in sheltered nooks everywhere [pg373] between tides.
It is essentially a tropical species of very wide and extended
range, but it does not occur north of St. Augustine. At Tampa it
has been found in vast numbers. (Plate LXIX.)

The California coast furnishes two more species of /Littorina/.
Their station is among the rocks between tides, and their habits
are quite the same as those of the east-coast species.

^L. scutulata.^ In this species the color is of various shades,
generally dark gray, mottled with white spots. A good-sized
specimen measures one half of an inch in length. The spire is high;
the columella flattened, broad; the shell is purplish-white within
the aperture. (Plate LXIX.)

^L. planaxis.^ Somewhat larger than the last; wider; with a lower
spire; grayish in color, sometimes speckled with white; chest
nut-brown within. The columella is remarkably flattened, and a
portion of the whorl next bordering the columella is excavated as
though eaten away by the animal. These two species are often found
associated on the rocks. (Plate LXIX.)

GENUS ^Lacuna^

Closely allied to /Littorina/ is the genus /Lacuna/, one species of which, ^L. vincta^, is very abundant on the New England coast. A curious and distinguishing feature of this genus is the umbilicus, which forms a lengthened groove along the columella. /L. vincta/ rarely exceeds one half of an inch in length, and is thin, with a pointed spire of five whorls. It is either of a uniform horn-color, or purplish, or banded with chestnut. It may best be found upon marine plants in sheltered places, or may sometimes be gathered in quantity from the roots of /Laminaria/ washed in by storms.

GENUS ^Tectarius^

The specific representatives of this genus are mostly tropical. ^T. nodulosus^ is abundant in Florida. It is about one half of an inch long, and has the flattened columella and round mouth characteristic of /Littorina/. It is decorated somewhat elaborately by revolving rows of nodules which cover the entire shell. Its station and habits are the same as those of /Littorina/.

FAMILY ~CERITHIIDAE~

In this family we meet with a somewhat new type of shell--the long, turriculate shell, with many whorls and with a channeled [pg374] aperture. The /Cerithiidae/ include a large number of genera, mostly tropical in distribution. Their shells are usually highly ornamented in various schemes of sculpture, but they lack beauty in color. The animal is provided with a siphon, as is indicated by the anterior canal of the shell. The operculum is corneous, with a nearly central nucleus.

GENUS ^Cerithium^

^C. floridanum.^ A very common species on the west coast of
Florida, also sparingly found at Hatteras. It has eight or ten
whorls, a gradually tapering spire, and a sharp apex; the aperture
is oblong, with a deeply cut anterior canal projected to the left
and backward (when the specimen is held apex up, with the aperture
toward the observer). The sculpture is elaborate, consisting of
many rows of revolving ribs, and close to the suture there are
circling rows of nodes. There is a curious hump just to the left
of the aperture, which is quite characteristic of the genus. The
color is whitish-gray; the length one and a quarter to one and a
half inches. Station, shallow water in lagoons and sheltered spots.
(Plate LXIX.)

^C. muscarum.^ Another Floridian species, somewhat smaller than the
last (one inch in length). It has heavy, prominent, transverse ribs
crossed by circling rows of chestnut spots, one heavy revolving
rib around the base; eight or nine whorls; a high-tapering spire;
and a sharp apex. The aperture is oblong, with the anterior canal
projecting to the left. The columella is arched; the color shining
gray to very light purplish. This very pretty little shell may be
gathered literally by the shovelful all along the west Florida
coast in sheltered spots, on sandy and shallow bottoms. (Plate
LXIX.)

^C. minimum.^ A still smaller Floridian shell, with jet-black
aperture and anterior canal projecting horizontally to the left.
The sculpture-plan is of revolving ribs and a series of white
granules just below the sutures. Its station is the same as that of
the last. Often the bottom of a lagoon will seem to be literally
paved with these somber-hued little shells. From Tampa Bay to
Charlotte Harbor they are very abundant.

GENERA ^Bittium^, ^Triforis^

These are allied genera, having numerous species upon our coasts, but the shells are so small that the inexpert collector is not likely to notice them. Hosts of these minute, turreted, decussated, blackish shells are to be found on the wiry grasses of salt-marshes. They are also found on algae at low-water mark. In /Triforis/ the whorls turn to the left. Range from Cape Cod to South Carolina. [pg375]

GENUS ^Cerithidea^

^C. scalariformis.^ This species has the suggestive outlines of the
family, but the aperture is simpler. The outer lip is considerably
thickened, sinuous, and yellow; there is a very slight notch at the
angle of the columella, and the lip serves for an anterior canal.
The apex is wanting by reason of the usual truncation of two or
three whorls of the spire. There are revolving ribs on the base;
longitudinal ribs elsewhere. The color is a dingy drab; within,
brownish-yellow. It is found in brackish water in Georgia and
Florida. This species is said to suspend itself from overhanging
vegetation by means of glutinous filaments. It may remain out of
water for an almost indefinite time. (Plate LXIX.)

^C. sacrata.^ A species very common on the mud-flats of San
Francisco Bay. It is a high-spired shell of ten heavily ribbed
whorls, with a series of revolving ribs on the body-whorl. The
outer lip is sinuous, and the columella is slightly twisted. It is
nacreous and brown within, dingy blue-black without. Length one
inch to an inch and a quarter. (Plate LXIX.)

FAMILY ~VERMETIDAE~

GENUS ^Vermicularia^

^V. spirata.^ This is a very curious creature when considered from
the point of view of the gasteropod mollusk. It seems at first as
though it would be better to regard it as a worm which had created
for itself a calcareous covering. But it is a true prosobranch
notwithstanding the fact that it has departed widely from the
conventional design in the fashioning of its shell. At first the
shell starts out in a regular form, and then the whorls become
separated, finally wandering about in a seemingly aimless manner.
The irregular prolongation sometimes measures ten inches in length.
The animal is in no way remarkable except in having the viscera
greatly elongated and the foot very short and broad. The color of
the animal is light brown with black spots; the shell-color is
rufous or ashy-white. Shells of this genus are often found grouped
together in an inextricable mass. It is found in shallow water from
New England to Florida.

FAMILY ~STROMBIDAE~

This is a particularly interesting family, but it is tropical, and is represented on the shores of the United States by only one [pg376] genus, /Strombus/, of which we have but a few species. /Strombus/ is a scavenger,--a buzzard among mollusks,--and its sense of smell is evidently very acute. Its eyes are much more highly developed than the usual gasteropod visual organs, and they are placed at the tip-ends of two very substantial eye-stalks or-pedicels. The tentacles are slender and project from the eye-pedicels. The foot is curiously developed; that portion of it which would naturally constitute the creeping-disk is exceedingly small, but the metapodium (the hinder part of the foot, upon which the operculum is situated) is very large. The corneous operculum upon its end, which is far too small to close the entrance of the shell when the creature retires within it, looks like a claw. Instead of creeping along the sand, /Strombus/ proceeds by jumps or awkward leaps, turning its heavy shell first to one side, then to the other. The shell is usually heavy, with the outer lip greatly thickened.

GENUS ^Strombus^