"STROPHIA CINEREA Novo.
Cinerous Strophia.
Fig. 35. A, front view; B, side view, both of the type.
DESCRIPTION.
SP. CH. Size, rather large. Shell, not present. Animal, dark brown in color. Whirls, ten. Examined 2,000 specimens.
Form of shell, cylindrical, the first three whirls being about equal in diameter, the fourth is but little smaller, then the shell slopes abruptly to a blunt point forming an angle of sixty-five degrees. The striations are quite numerous, twenty-five on the first whirl, rather prominent, regular, arranged in lines, slightly inclined from right to left and a little narrower than the interspaces between them; they are not furrowed, but are rounded and smooth.
Aperture, rather small, rather open, but narrows quickly from the entrance. Lower tooth, not prominent, short, about 04 high, a little more than twice as long as high, and its position is about central, but quite near the frontal bar, about .07 ; it is not elevated; the upper is represented by a slight protuberence.
Margin produced forward as far as the diameter of the shell, slightly inclined to the right a trifle beyond the diameter of the shell, is thickened only on the left side, and here but slightly, about .03. On the right it is reduced into a sharpened edge that projects forward; on the left the margin is smoothly rounded, but behind it is developed a roughly sharpened lateral edge. The frontal bar is narrow but prominent, projecting well forward, completely interrupting the striations.
Color of shell, pale brown, somewhat mottled with white, but with the striations ivory white. Internally, light brown, becoming a little paler on the margin.
DIMENSIONS.
Size of type, 1.15 by .45. Largest specimen, 1.15 by .49. smallest, .83 by .37. Greatest diameter, .50; smallest, .36. Longest specimen, 1.23 ; shortest, .83.
OBSERVATIONS.
There is considerable individual variation even in the type locality of this Strophia, and, judging from my past experience with this species, which extends over a period of about ten years, there is some danger of the type form becoming extinct. Of this matter, however, I shall be able to speak more positively, I trust, in my next instalment of this Monograph, the inclinations being to a form with coarser striations and fewer of them. There are also three decided forms which are as follows:
No.1 is a small form, .83 by .37, with numerous striations, twenty-nine to the first whirl; aperture, more contracted, with a thinner margin and with the color white, slightly mottled with very pale brown. This form occurs in the type locality, and forms about fifty per cent. of the whole number found.
No.2 is about the same size and form of the type but much darker in color, the interspaces being dark brown, and the striations pale brown; the interior is also dark brown, pale on tooth and margin, nearly white on lower side of frontal bar. The striations are narrower, being about one half the width of the interspaces. This form occurs along the beach of Middle Bay, Hog Island, east of the type locality, and is not very common, being about five per cent. of the type form.
No.3 is a heavy shell, shorter and thicker than is the type, 1.10 by .40, with a thick double margin (.10), short, prominent central tooth and very narrow projecting frontal bar. The shell is white, mottled with very pale brown. Of this singular form I have two only, and they came from the northward of the type locatity.
Strophia cinerea may at once be distinguished from all other members of the genus by the thin margin, thickened slightly to the left, which is produced well forward, cylindrical form and peculiar color. No other Strophia, with which I am familiar, combines these characters in one species.
This species, being from an accessible locality, is quite common in collections, but in all of the cases where I have seen it labled it has erroneously borne the name of some of the older species which are from widely different localities.
The species has been known for many years, and we find it figured by Edmund A. Crouch, in his introduction to Lamarck's Conchology, in 1827, plate XV, No. 2, as S. mumia! (See remarks regarding this on page 194 of Vol. I..)
HABITS AND DISTRIBUTION.
This singular and interesting Strophia occurs on Hog Island, along the shore of Middle Bay, which is on the south side of the key. The shells are found either on the ground or attached to the stems of low bushes not far above the ground. I traced them about a hundred yards along the bay in either direction; to the eastward they straggle
out somewhat and grow into form No.2, but to the westward terminate more abruptly, and do not occur far up the slope of the hill, which lies to the northward, excepting as stragglers, to be mentioned under head of the next sub-species."
