Strophia intermedia Maynard, 1889

Original Description


Small Rough Strophia.

Plate II, 3 & 3B, shell.


            SP. CH. Size, rather small. Shell, quite thin and not very robust. Striations, present and coarse. Tentacles, not very short, about one third as long as the eye peduncles. Examined 3,000 specimens.

            Form of shell, short oval, the greatest diameter being on the second whirl, the first and third being very little smaller, and from this the shell tapers to a rather blunt point at the apex, forming an angle of about 60 degrees. There are 16 coarse, widely separated striations, some of which are omitted, and none of which form regular lines, but are somewhat inclined from right to left. The striations are wide, meas­uring .03, and are generally furrowed longitudinally on top, but the edges are rounded. The sutures between the whirls are not very deep.

            Aperture, rather small, but not contracted within. The central tooth is prominent and long, extending back into the shell .18, and its position is central; the upper tooth is placed just above it, and al­though it is not prominent, is long, and takes a turn around the column.

            The margin is not produced forward quite as far as the diameter of the shell; it is not greatly thickened, measuring .06, and the posterior portion is produced backward into a thin, though not prominent edge. The frontal bar is moderately developed, and the striations are inter­rupted, not appearing within it. The striations on the back of the shell may be seen within the aperture, when held against the light. The ani­mal is not very large; eye peduncles, .15 long; tentacles, .05; jaw, as in S. copia.

            Color, white, with an occasional spot of purplish between the stri­ations, and with the apex flesh color; internally, purplish brown which fades as it approaches the teeth, and does not extend beyond them; thus both they and the portions beyond them are pale flesh color. Color of animal, pale brown, with a V-shaped mark on the back, of the same color but somewhat darker.


            Sizes of types, .90 by .40 and .88 by .40. Largest specimen, 1.04 by .44. smallest, .82 by .40. Greatest diameter, .47; smallest, .38. Longest specimen, 1.04; shortest, .82.


            Although the great majority of specimens of this species, are con­stant to the type, yet variation is very great, some specimens before me ranging from cylindrical, with the three first whirls of the same size, to those that are nearly top-shaped, having the first whirl the largest, with all gradation between. The margin varies in thickness, .12 being the extreme width. In color the tendency is to become whiter than the type, with no spottings and no fleshy tintings on the apex. The whirls are almost invariably ten but are rarely eleven. The striations vary from 16 to 19, but in all of this variation, the only decided form, is one that lives on stunted vegetation which is found in exposed situations on rocks; these are white with a heavy shell, through which the striations cannot be seen when held to the light. Some shells are not long but quite thick in diameter when compared with the type.

            The Small Rough Strophia is found on the low vegetation that grows on the margin of the beach on the south side of Little Cayman.

            The top-shaped form mentioned is very rare and is probably the results of an injury that the animal received, causing it to form a mar­gin to the shell when it was not fully grown.

Distinguished from S. pannosa by the smaller size, thinner shell and margin, and more open aperture; from copia, which it resembles in size, by the smaller number of striations, 16 to 19 instead of 22 or more. The interspaces in this species are wider than the elevated striations, while in copia the reverse is the case.

            Known from all other species by the rather small size, elongated teeth, irregular, widely separated, coarse striations, and white color.


            The Small Rough Strophia is found on the coast of the south side of Little Cayman, west of a large mangrove swamp that nearly divides the island into two unequal portions, and along the beach on the south side of Cayman Brac, as far east as the cocoa-nut grove extends, now about half the length of the key.

            They are much more common than the Ragged Strophia, and al­though they mingle occasionally with the colonies of the Common Stro­phia that border the shore, they are never found far from the beaches. They are more common on Little Cayman than on Cayman Brac; see further remarks under habits of S. copia." (Maynard, 1889:13-15)

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