Chapter C: W. JOHNSON, Business Manager, (2)

Anal opening with small papillae, branchial opening with well developed papillae. _Palpi_ as usual, their posterior margins connected for about one third of their length or less.

As to the color of the soft parts, which is so characteristic in _barnesiana_, not much can be said, since my material has been too long in alcohol. But in most of my specimens the gills are yet distinctly suffused with black. The placentae have been rendered whitish, but here and there traces of a dark stain are preserved (which is disappearing gradually). It is quite possible that the color of the placentae originally was similar to that of _barnesiana_.

The _glochidia_ are subelliptical, slightly higher than long; L. O. 15, B. O. 18, thus agreeing with those of _F. barnesiana_.

NOTE ON THE RELATION OF SNAIL FAUNA TO FLOODS.

BY A. RICHARDS.

During the years 1911 to 1916, while the writer was a member of the faculty of the University of Texas, a series of incidental observations on the snail fauna of Waller Creek was made. These observations have now come to an end due to the change of residence of the observer. It seems not unwise, therefore, to publish a short note on the subject in the hope that the facts recorded, although fragmentary, may have a bearing on the work of some other follower of snail life.

Waller Creek is a small stream near the University of Texas at Austin. It is some four miles in length and empties into the Colorado River at a distance of perhaps two miles below the University. That portion of the stream close to the University between Fifteenth and Twenty-seventh Streets, was most closely observed, but data was also collected from the region below. During the hot months, from about July 1st to October 1st usually, the stream is dry, or water is to be found only in an occasional pool; during the rest of the year the water flows to a depth of a few inches. The bed is scoured out of limestone (Austin Chalk) and has for much of its length a solid flat rock bottom. The banks of the creek have in general a gradual slope. In time of flood and during heavy rains, this stream rises very rapidly and quickly becomes bank-full, so that the water rushes down in a torrent, the roar of which may at times be heard for a distance of some blocks. The fall of the creek is considerable, being about 75 feet in two miles from Twenty-seventh Street to the Colorado, and this fall in connection with the shape of the bed gives to the current in times of flood a tremendous force.

During the first two years of this observation, 1912‒1913, the snail population of the creek in its middle stretches was dense. There were in particular two species very thickly represented, _Planorbis lentus_ and _Physa halei_. So numerous were they that one could in a few moments within a very few feet gather a pint of either kind. Wherever a little ripple or a tiny waterfall occurred were many snails oriented in relation to the current, their heads pointing into it. Elsewhere in the more quiet water they were also to be found, but in less numbers. These conditions obtained especially in the early spring; as the breeding season, which in that latitude extends over half the year, passes by, the snails of course become much less numerous.

It is to be noted that previous to the time when the snails had become so abundant, there had been no heavy rains of sufficient importance to be recorded since 1908. Excessive rains occurred in May 1908, November and May 1907, June and March 1905, May and April 1904, July and February 1903, July and November 1902. There was a very severe flood in the creek in April 1900. It will be seen that between the time when my observations began and the last excessive rain considerable time had elapsed and the snails had had the opportunity to reinstate themselves in the creek, assuming that they had suffered in those floods as they have done in the later ones.

In the fall of 1913 there were two floods of unusual proportions in the creek. In October it rose very rapidly, but shortly subsided, and in November, at the time when the entire state was visited by the most severe flood since 1869, it was again subjected to a very thorough scouring. Excessive rains fell on several consecutive days, and streams in the entire Colorado watershed were out of their banks.

After the heavy rains of the earlier part of the month there were several days upon which the rainfall, while comparatively light, was sufficient to keep the creek much higher than its normal level. When the water finally subsided to its normal amount the bed was covered completely with a layer of detritus and soft green humus and algae from a half an inch to an inch in thickness. This deposit and the acids formed from it have been the cause of a much more rapid disintegration of the limestone than had been the case in the immediately preceding years. Loose pieces of limestone which were exposed to the action of the water had in many cases fallen apart by the end of January. Further rises occurred on April 27 and on May 20th, 1914, but were not sufficient to remove all of the accumulated layer of detritus.

In January 1914, a search for snails where they had before been numerous failed to reveal a single specimen of _Planorbis_ and less than half a dozen _Physa_. Even in the deeper pools they could scarcely be found. Later in the spring in the lowest part of the stream a number of very small _Physa_, as well as some clusters of eggs were found. The force of the current had been so great as to wash the snails down to the river, and it is possible that the condition of the water due to the decomposing humus may have affected those which were able to escape the flood danger. That some of the Physa were left after the flood may be attributed to their pointed shape which decreases the amount of force that the water was able to exert on them as compared with that on the flat Planorbis shells. Except as noted above in April and May 1914, the conditions in the creek remained as normal.

In January 1915, Physa has again made its appearance in the middle parts of the stream, although in small numbers only. Diligent search, however, failed to reveal a single Planorbis. The snails which were present were found only under fair-sized rocks where they were well protected; they did not occur out in the open stream as had been the case when the creek was more densely populated with snails.

In April 1915, on the 22d and 24th, Waller Creek was swept by three scouring floods which devastated the entire bottoms. The water rose higher during the night than it had at any time since 1886; bridges were washed away and much damage done. The bottom of the creek was again washed clean except under the larger stones and in deep holes in the bed. Snails were not observed in any numbers following this flood during the rest of that year. Early in January 1916, however, Physa had again appeared fairly abundantly where they had formerly been very thick, in the region just above the University; later in the spring they became quite numerous here. In January of this year the first Planorbis were found that had been seen in the creek since the autumn floods of 1913. Between Fifteenth and Sixteenth Streets in a pocket containing good-sized stones over which the water flows rather swiftly a number of specimens were taken, although none were found above or below this locality. It is noted that below this region the creek is frequently covered with oily scum and that it receives the refuse from the adjoining properties. Except after high water which would clean it out, the creek in this region would hardly be expected to support much snail life. It must be supposed either that the Planorbis had made their way up to Sixteenth Street during the short time following the floods before the water became badly contaminated, or else that in this particular place a few specimens from the previous years had withstood the floods and reproduced themselves in sufficient numbers to be noticeable in January. Of these two suppositions the latter seems much the more rational.

After the flood of 1915 the water subsided very quickly so that a new layer of humus and algae was not deposited, but that the bed was again restored to its former condition of a clean smooth rock bottom. Upon the return to this condition the snail population increased very rapidly, and at the time when the last observation was made in the early summer of 1916, seemed in a fair way to return to the condition of 1912.

It seems to the writer that the slow return of the snails during the year 1914 was due not only to the repeated rains of the fall and winter of 1913‒14, but also to the condition of the creek bed at this time. Although the heavy rains of 1915 were more severe, they were confined to one month, and the creek bed was left in a very much cleaner condition than during the preceding year.

The conditions of life which obtain now in Waller Creek are those of a new life region. This must of necessity be so in an intermittent stream to a certain extent, but owing to the flood conditions here they are doubly so.

The chief facts of interest in regard to the habits of snails as shown by these observations, are these: 1, The snails of both species are to be found commonly in uncontaminated water which is running at a fairly rapid rate, and the most common orientation is with the heads pointing up stream; 2, The snail population in any stream is subject to wide fluctations depending upon flood conditions; 3, Physa because of its shape is less affected by floods than Planorbis; 4, The return of the snail population to a given stream is determined not only by the frequency and severity of the floods, but also by the condition of the bottom of the stream after the subsidence of the high water; 5, The snails thrive best where there is a constantly renewed supply of clean water which contains little decaying vegetation.

_Wabash College, Crawfordsville, Ind._

WILLIAM BULLOCK CLARK.

Dr. William Bullock Clark, professor of geology in the Johns Hopkins University, eminent for his contributions to geology, died suddenly from apoplexy on July 27, at his summer home at North Haven, Maine.

Wm. Bullock Clark was born at Brattleboro, Vermont, December 15, 1860. Since 1894 he was professor of geology in Johns Hopkins University. In 1896 Professor Clark organized the Maryland Geological Society, and has been State Geologist since that time. The admirable volumes on paleontology of Maryland, issued under his direction, are widely used by conchologists interested in fossil mollusks. This series of reports will be his enduring memorial. Professor Clark’s chief paleontological interest was in the _Echinoidea_, upon which he published several monographs.

PUBLICATIONS RECEIVED.

A MONOGRAPH OF WEST AMERICAN MELANELLID MOLLUSKS. By Paul Bartsch (Proc. U. S. Nat. Museum, Vol. 53, pp. 295‒356, pls. 34‒39, Aug. 1917). This completes the discussion of the West American mollusks of the super-family Pyramidelloideae, comprising the family Pyramidellidae, which has been previously treated, and the Melanellidae here considered. The former are readily distinguished by having the “nepionic whorls sinistral and tilted; the axis of the early whorls usually being at right angles to that of the succeeding turns, in the first of which the nuclear whorls are frequently quite strongly imbedded.” In the latter the early whorls are dextral and never tilted or immersed. A review of the work done in this group is followed by the descriptions of the species, including forty-nine new species and one new genus _Eulimostraca_. The illustrations are excellent.

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NEW AND LITTLE KNOWN SPECIES OF SOUTH AMERICAN MUSSELS OF THE GENUS DIPLODON. By William B. Marshall (Proc. U. S. Nat. Museum, Vol. 53, pp. 381‒388, Pls. 50‒55, August, 1917). Two new species _Diplodon felipponei_ and _D. fortis_ are described and figured, together with six species described by Mr. C. T. Simpson in his Descriptive Catalogue of the Naiades and not previously figured.

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NOTES ON THE SHELLS OF THE GENUS EPITONIUM AND ITS ALLIES OF THE PACIFIC COAST OF AMERICA. By William H. Dall (Proc. U. S. Nat. Museum, Vol. 53, pp. 471‒488, August, 1917). An interesting account of the various groups and subgenera is followed by descriptions of forty-two new species.

The name Pictoscala is proposed for a section, type _Scalaria lineata_ Say.

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STUDIES ON AUSTRALIAN MOLLUSCA. PT. XIII. By C. Hedley (Proc. Linn. Soc. New South Wales, 1916, vol. 41, pt. 4, pp. 680‒719, pls. 46‒52, issued April 4, 1917). The author’s notes under _Tridacna gigantea_ Perry are of such general interest that we quote them in part. “Under the name of _Chama gigas_ the father of Natural History seems to have embraced the whole of the modern genus _Tridacna_. For the name _gigas_, as restricted to a single species, the candidates are the shell subsequently named _squamosa_ by Lamarck and a huge species whose valves in the Ulrica Museum, together weighed 498 pounds.

“After careful examination, Hanley decided that the furbelowed clam, such as Reeve has figured for _T. squamosa_, ought rightly to bear the name _gigas_. He based his verdict on the ground that the actual shell owned by Linné as representing _gigas_, is the Lamarckian _squamosa_, and that to this apply most of the literary references. Linnean contemporaries such as Born, Regenfuss and Chemnitz, while making casual references to the giant, all agree in figuring and describing _squamosa_ as the Linnean _gigas_.

“Discriminating in 1819 between the species his predecessors had confused, Lamarck unlawfully used the name _gigas_ for the largest form, while for the Linnean _gigas_ he proposed _squamosa_. Attentive to the remarks of Hanley, Hidalgo in 1903, renamed the biggest species _T. lamarcki_. But in 1811, Perry had already used the name _Chama gigantea_ for ‘the largest shell at present known.’ As the young of the giant has not yet been traced to the adult, it is still possible that _squamosa_ is a juvenile deeper-water form of the large intertidal and abraded _gigantea_.

“The heaviest known are a pair weighing 550 lbs., which Cuvier and Lamarck relate were presented by the Venetian Republic to Francis I. These still exist, their edges bound with brass, as holy-water basins in the cathedral of St. Sulpice, in Paris.

“The photographs of Saville Kent show the giant clams in their natural position on the Great Barrier Reef, where they occur free and exposed at low tide, standing on their umbones, and showing their brightly colored mantle and so-called eyes as they gape.”

There are many other interesting notes bearing on nomenclature, and the animals of Australian species. Six new species are described and twenty-nine species figured.—C. W. J.

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AN ANNOTATED LIST OF SHELLS FROM NORTHERN MICHIGAN. By Mina L. Winslow (Occasional papers, Mus. Zool., Univ. Mich., No. 42, July 1, 1917) a list of sixty-five species from Schoolcraft, Alger and Chippewa counties, also a list from Isle Royale.

NOTES.

THE OLDROYD COLLECTION.—Mr. and Mrs. J. S. Oldroyd have given their collection of shells to the Leland Stanford Jr. University, and are now permanently employed in the Museum, Mrs. Oldroyd being the curator. The collection has been placed in the Department of Geology and Mining. The Stanford alumni purchased the collection and library of the late Henry Hemphill, which, with the Law collection and several others, forms an unusually fine working series. Mr. and Mrs. Oldroyd have spent about eight weeks at Friday Harbor, Puget Sound and British Columbia making large collections for the Stanford University, California Academy of Science and University of California.

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NORTH CAROLINA LAND SHELLS.—The following species of land shells were picked from leaf-mold collected at Spruce Pine, Mitchell Co., North Carolina, by Samuel G. Gordon while on a mineralogical excursion. The specimens are in the collection of the Acad. Nat. Sci., Phila., _Gastrocopta contracta_ Say, _G. pentodon_ Say, _Circinaria concava_ Say, _Polita indentata_ Say, _Taxeodonta lamellidens_ Pils., _Gastrodonta elliotti_ Redf., _G. guldaris_ Say, _Euconulus sterkii_ Dall., _Punctum pygmæum_ Drap., _Carychium exile_ Lea.—E. G. VANATTA.

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A CORRECTION.—In my little paper, “Descriptions of New West American Marine Mollusks and Notes on Previously Described Forms,” Proc. U. S. Nat. Mus., Vol. 52, pp. 670‒671, plate 46, figure 2, 1917, I published _Cerithiopsis (Cerithiopsis) helena_ from Panama, type Cat. No. 204128, U. S. N. M. Mr. Vignal, of Paris, has been kind enough to call my attention to the fact that the same combination was used by O. Boettger in 1901 for a fossil in his contribution “Zur Kenntnis der Fauna der mittelmiocänen Schichten von Kostej im Krassò-Szörényer Komitat,” in “Verhandlungen und Mitteilungen des siebenbürgischen Vereins für Naturwissenchaften zu Hermannstadt,” p. 128, 1901. It is therefore necessary to bestow a new designation on my shell, and it may be known as _Cerithiopsis (Cerithiopsis) anaitis_.—PAUL BARTSCH.

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ALBINISTIC EPIPHRAGMOPHORA FIDELIS.—A few days ago, I had two hours in Gladstone Park. The Park is wooded, and there are large moss-covered rocks. _E. fidelis_ was out freely. I found one light one. The one sent you some years ago was uniform in color. This one shows two distinct dark narrow bands around the lower whorl, but not showing anywhere else. This is the fourth one I have found in the Park in twenty years or more, though I have been there often.

—J. G. MALONE, _Portland, Ore._

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The many friends of DR. HERMANN VON IHERING will hear with deep regret that he has been removed by political intrigue from his position of Director of the MUSEU PAULISTA at Sao Paulo, Brazil. This museum was founded by Dr. von Ihering. His eminence as a zoologist and unceasing activity as an investigator of the South American fauna, had won for it an honorable place among scientific institutions. We understand that his successors are men without knowledge of the biological sciences. As the only scientific assistant, Mr. Rudolph von Ihering has resigned, it appears that the scientific activity of the State Museum of Sao Paulo has come to an end—a real calamity to American zoology and paleontology.

Dr. von Ihering is located at present at Hansa de Joinville, State of Santa Catharina. He is in good health, and is engaged in the preparation of his work: “Die biogeographischen Grundgesetze,” several chapters of which will deal with mollusks.—H. A. P. & C. W. J.

PLATE VII
]

1, 2. PSORONAIAS KUXENSIS FRIERSON.

3. EPIPHRAGMOPHORA CALLISTODERMA PILS. & FERR.

4. UNIO TETRALASMUS SAY.

5, 6. ZACHRYSIA RAMSDENI PILS.

7. Z. EMARGINATA PFR.

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Footnote 1:

NAUTILUS, vol. xx, pp. 58‒60.

Footnote 2:

NAUTILUS, xxvi, pp. 51‒55, 1912.

Footnote 3:

In a later work Ortmann classifies both _ventricosa_ and
_cohongoronta_ as varieties of _ovata_ Say.

Footnote 4:

The relations of mollusks to fish in Oneida Lake. By Frank Collins
Baker. Technical Publication No. 4, New York State College of Forestry
at Syracuse University. Pp. 366. Syracuse, N. Y., 1916. We are
informed that it may be obtained free by those interested in the study
of Mollusca by applying to the dean of the college, Dr. Hugh P. Baker.

Footnote 5:

_Pupa griqualandica_ M. and P., 1893; the specimens used being from
Pretoria.

Footnote 6:

Ann. Mag. N. H. (8), i, p. 76, pl. i, 1908.

Footnote 7:

In NAUTILUS, 28, 1914, p. 31, I have described the anatomy of
“_Pleurobema fassinans_.” This is a mistake: the shells examined
belong to _Pleurobema_ all right, but are the form known as _U.
argenteus_ Lea, which belongs to the _oviforme-group_, and should be
called: _Pleurobema oviforme argenteum_ (Lea). These will be treated
more fully elsewhere.

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TRANSCRIBER’S NOTES

1. Silently corrected typographical errors. 2. Retained anachronistic, non-standard, and uncertain spellings as printed. 3. Footnotes have been re-indexed using numbers and collected together at the end of the last chapter. 4. Enclosed italics font in _underscores_.