On a New Genus of Terrestrial Mollusca Inhabiting California.
BY J. G. COOPER, M.D.
Binneya Cooper.[4]
Generic characters.—General form of animal like Limax, with a shell resembling that of Omalonyx or Lamellaria.
Body about three times as long as shell, semicylindrical, obtuse in front, forming an acute angle behind; foot extending the whole length, somewhat distinct anteriorly, and carinate behind. Mantle shield-like, covering the back anterior to the shell for about one-fourth its length, not reflected over the shell. Eye-peduncles moderate, slender, two short acute tentacles in front of head. Lingual teeth resembling those of Helix in form and arrangement.
Shell entirely external, ear-shaped, nearly flat, about one-third as long as the animal, which it does not half cover when retracted. Spire flattened, forming two horizontal volutions, last whorl enormously expanded and slightly arched. Columella distinct, entire, hiding the interior of the convolutions.
Binneya notabilis Cooper. State Coll. Species 988.
Specific characters.—Animal dark lead-colored, with black reticulations, and a wide brown stripe along the median line, extending from the mantle to the front of head, about one-fourth of the total length.
Shell with a pale brown, smooth and shining epidermis, extending beyond the margin, translucent when young, becoming thickened by an opaque white deposit on the interior when old. First whorl or nucleus ornamented with about thirty delicate parallel revolving ribs, not concealed by the epidermis, and ending abruptly at the commencement of the transverse lines of growth in the body whorl.
Length 0.46, breadth 0.34, height 0.12 inch.
This genus resembles Limax in its shield-like mantle, but in the more essential characters of the lingual teeth, appears to belong undoubtedly to the Helicidæ. It approaches nearest to the subfamily Vitrininæ, in having the mantle in front of the shell, approaching nearest to the Daudebardia of Europe; but differs in the form and opacity of the shell, which resembles some of the Succininæ, especially Omalonyx of South America, etc. It differs from these very much in the form of the animal, and the shell being wholly external, forming one of those connecting links which make it difficult or impossible to divide the Helicidæ into distinct groups.
Habitat. So far this animal has been found only in Santa Barbara Island, one of the group within this State. It there inhabits but one station, so far as I could discover after very careful search. That is the head of a ravine facing the south-east and about two hundred and fifty feet above the sea. During the wet season there may be a little water springing from this place, but for at least five months it is not even damp, while the remainder of the island is entirely destitute of water. Myriads of Helix kelletii and two other species (probably new) inhabit it, but during the dry season retire into a torpid æstivation, not disturbed by the fogs and mists of summer. The Binneya, the rarest of all, and not protected from drought by its shell, burrows down to the under surface of thick succulent roots, and contracting to about twice the size of its shell, covers the rest of its body with a white mucous secretion, which appears to be impervious to the moisture within, and dries into a tough leathery shell.[5] When moistened for a few hours, the animal separates the edge of this box from that of its true shell, and becomes active.
The figures [[Fig. 15]] represent three positions of the shell, the animal æstivating and also crawling.
Fig. 15.
I found but three alive, and eighteen dead shells.
[4] To all those who have seen the splendid works on the “Terrestrial Mollusks of the United States,” by the late Dr. Amos Binney, so ably continued by his son W. G. Binney, the appropriateness of the name will be at once evident.
[5] In this it resembles the Testacellæ of Europe, which are otherwise very different.
Dr. Trask presented, in the name of Mr. Garrett, the following paper: