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Read Ebook: The Nautilus. Vol. XXXI No. 2 October 1917 A Quarterly Journal Devoted to the Interests of Conchologists by Various Johnson Charles Willison Editor Pilsbry Henry Augustus Editor
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Ebook has 139 lines and 17614 words, and 3 pages
William Bullock Clark 68
Publications received 69
Notes 71 ???????????????????????????????????????????????????????????????????????
C. W. JOHNSON, Business Manager, Boston Society of Natural History, Berkeley Street, Boston, Mass.
Entered as Second-Class matter at the Boston Post-Office.
The Cruise of the "Tomas Barrera"
This is the narrative of a scientific expedition to Western Cuba and the Colorados Reefs, with observations on the Geology, Fauna, and Flora of the region, undertaken in May and June, 1914, under the joint auspices of the Smithsonian Institution and the Cuban Government.
ALL BOOKSELLERS
NEW SHELL LISTS FREE.
A new list of Philippine Land Shells covering many of the most beautiful forms at greatly reduced prices. A list of 2,000 species of shells, priced at 5 to 10 cents per species. Two lists of the finer cabinet shells, the more aristocratic forms. List of American Land Shells. Illustrated list of Philippine Shells. Further lists in preparation. I desire correspondence with collectors who wish to build up large and extensive cabinets. I have in stock over three times as many species as are covered by my lists. Collections of a strictly scientific nature purchased for cash.
WALTER F. WEBB,
ROCHESTER, N. Y.
Exchange notices not exceeding three lines will be free to subscribers as long as space will allow.
FOR EXCHANGE: Marine shells from various parts of the world, for others. Send lists.
J. R. LEB. TOMLIN, 120 Hamilton Road, Reading, England.
THE NAUTILUS.
NOTES ON THE VARIATION OF ISCHNOCHITON CONSPICUUS CPR.
BY E. P. CHACE.
To the naturalist the study of variation and environment and their relation to each other is always interesting and to the conchologist who studies his shells in their natural surroundings as well as in the cabinet many things are revealed. It is not, often, however, that variation in form may be so easily traced to qualities of environment as in the following instance.
While cleaning a lot of this species taken at San Pedro last fall two specimens were noticed which differed so widely from the others that they might easily have been mistaken for another species. They were much wider and lower-arched than the typical form and the posterior corners of the valves were rounded off, making the lateral areas very narrow.
In color pattern, sculpture, and mantle characters these specimens were identical with those from the tidepools, and, as will be seen by referring to the table of measurements, the smaller specimens approach quite closely to the proportions of the typical or tidepool forms.
TYPICAL OR TIDEPOOL FORMS. ? SPECIMENS FROM PHOLAD HOLES. ?
In brief, Lot 1 shows an angle of divergence constant at 125? to 130?, where Lot 2 shows an angle varying from 130? to 155?, and a proportion of length to width 2.51 to 2.80 as against a proportion ranging from 2.47 to 1.93.
The noticeable differences to the eye are first, the narrow and sharply raised lateral areas, and second, the shape of the posterior edge of the median valves. In the tidepool specimens the posterior or exposed edge of each valve is a straight line, while in specimens from the pholad holes this line becomes a double convex curve, the most posterior portion of the valves being about midway between the beaks and the girdle.
These differences seem to be explained by the following facts. In collecting, the tidepool specimens are usually found on the under side of large rocks and well back from the edge. This situs protects them from the light which they evidently find objectionable, but it makes necessary a nightly journey of about two feet to the nearest growth of algae on which they feed. This activity stretches the girdle downward from the edges of the valves and permits a free play of all the valves so that the mantle deposits its shelly secretions according to the normal habit of the species. The specimens living in the pholad holes, however, apparently never leave them as they are frequently found feeding on the fucus which overhangs them. It protects them from the light, so they have no occasion to move about, and the sand which is washed down into these burrows would make re-entrance almost impossible. A series of these specimens shows a gradual change of form. The young specimens are very similar to young specimens from the tidepools, but as they increase in size they become crowded so that the valves press against each other, especially at the posterior end where the valves are bent back across the bottom of the hole. This crowding of the valves upon each other and the crowding of the girdle against the outer edges of the valves so displaces portions of the mantle as to cause the changes noted above.
Several specimens from each situs were disjointed and a study of the individual valves showed that those from pholad-hole specimens were thicker and had shorter sutural plates and a wider sinus, this last being especially noticeable in the valves from the posterior end. Apparently this change in the sinus is the result of the broadening of the connecting ligaments due to compression by the crowding valves.
A count of the insertion plates of these disjointed specimens was made and considerable variation noticed. So much, in fact, that more specimens were pulled apart for the express purpose of counting these plates. Representative counts were as follows: 9 slits on the anterior valve, 2-3 on the median valves, and 10 on the posterior. Others show 12, 2-3, 8; 11, 2-3; 14, 3-4, 11. Absolutely no difference in this character could be found between specimens from the tidepools and those from the pholad holes.
On page 64 of vol. xiv of the Manual of Conchology, Dr. Pilsbry says, "Carpenter has given a varietal name to a broad, worn specimen which he thus describes:
LAMPSILIS VENTRICOSA COHONGORONTA IN THE POTOMAC RIVER.
BY WILLIAM A. MARSHALL.
September 4, 1909. Potomac River, Hancock, Washington, Co., Md. .
May 9, 1911. South Branch, Potomac River, Southbranch, Hampshire Co., W. Va. .
August 16, 1911. Shenandoah River, Harper's Ferry, Jefferson Co., W. Va. .
May 6, 1912. South Branch, Potomac River, Romney, Hampshire Co., W. Va. .
Dr. Ortmann remarked "It is probable that this species will turn up elsewhere in the Potomac. The localities known at present are all to the west of the Blue Ridge Mountain, that is to say, within the Great Alleghany Valley and the Alleghany Mountains."
When found the two valves were separated, but so accurately do they fit together that it is evident they belong to the same individual. The fact that the valves were separated and yet were found near each other is additional evidence that they had not been transported any great distance by currents. At any rate this is the first recorded finding of the species in the Potomac River so far south as Great Falls.
The specimen is rather a small one. It measures, length 71 mm.; height 47 mm.; diameter 28 mm. It is in the collection of the U. S. National Museum, catalogue number 273834.
COLLECTING DAYS ABOUT THE NAVAL STATION, GUANTANAMO BAY, CUBA.
BY JOHN B. HENDERSON.
In March last, while waiting for a boat to take us to Haiti, Dr. Bartsch and I spent nearly three weeks at the U. S. Naval Station at the entrance to Guantanamo Bay. We employed our time in exploring the country about and subjecting it to a high degree of intensive collecting. In this eastern corner of Cuba the coastal strip of some ten miles in width is a semi-arid region with a complex of mountains that are either quite bare of trees or, at most, covered with a scrub forest and low-growing spiny shrubs, with, here and there, a wealth of cacti that almost suggests Lower California. The rock foundation of all this region,--barring some shore strips of very recently elevated coral, is everywhere composed of about everything in the line of rocks except limestone. This is a condition that in the Antilles usually spells disappointment and failure to the snail hunter. North of the big bay and then across several miles of low flat country, just where the foothills of the sierras begin, lies the city of Guantanamo, interesting to us as the home of Charles Ramsden, the naturalist. Just north of Guantanamo is a great rampart of high limestone mountains which beckon most alluringly to the collector. Sections of this rampart, somewhat arbitrarily marked off, are the "Monte Verde," the "Monte Toro" and the "Monte Libano" of classic fame in Cuban Natural History.
In company with Ramsden we spent a wonderful day on nearby Monte Libano but a revolution that was then devastating the province and filling the land with incendiaries and bandits drove us out of this richer field and obliged us to confine our attentions thereafter to the arid country lying within the safer limits of the Naval Station,--some fifty square miles upon which Uncle Sam holds a long lease.
It seems to be a natural law that arid or desert lands support but few species of snails, but that these few species exist in great numbers and that they take on a very considerable range of variation. All this is perfectly true of this region. We were constantly amazed by the great number of specimens to be found; and each day of exploration in some new valley or over some range of hills added even greater figures of abundance to our already astonishing records.
AMNICOLIDAE FROM ONEIDA LAKE, N. Y.
BY HENRY A. PILSBRY.
AMNICOLA BAKERIANA, n. sp.
Length 4.3, diam. 2.7 mm.; 5 whorls .
Length 3.75, diam. 2.3, length of aperture 1.35 mm.; 4 2/3 whorls.
Length 4.1, diam. 2.75, length of aperture 1.65 mm.; 4 2/3 whorls.
Oneida Lake; off Short Point in 8 1/2 ft., mud bottom. Lower South Bay, in 18 ft., on mud bottom.
AMNICOLA CLARKEI, n. sp.
The shell is narrowly umbilicate, conic, a little obtuse at the apex, corneous, nearly smooth. The whorls are very convex, separated by a deep suture, the last whorl tubular. The aperture is distinctly oblique, almost circular, the upper end rounded, but a trifle more narrowly so than the base. It projects but little beyond the preceding whorl laterally. The peristome is thin, continuous, scarcely or barely in contact with the preceding whorl above.
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