Strophia eximea Maynard, 1894

Original Description

"STROPHIA EXIMEA Novo.

Choice Strophia.

Fig, 59. A, front, B, side view of type.

DESCRIPTION.

            SP. CH. Size, medium. Shell, not very thick. Striations,

present, but very fine. Whirls, ten. Examined 1,000.

            [Note. This species and the next following belong to a peculiar group of Strophias, which may, with perfect propriety, be placed in a separate sub-genus which may be characterized as follows:

6. MULTOSTROPHIA.

CENTRAL TOOTH, SLIGHT, NOT THICKER THAN HIGH, STRIATIONS, NUMEROUS, EXCEEDINGLY FINE AND POLISHED. Type, Strophia eximea Mayn. Locality, Bahamas.]

            Form of shell, cylindrical, with the first three whirls equal in diameter, then the shell slopes gradually to a blunt point, forming an angle of sixty-five degrees. The striations are very numerous, fifty to the first whirl, they are rounded, regular, being half cylinders, and they are very slightly inclined from right to left.

            Aperture, large and open. Lower tooth, small, .03 high, thinner than high, but about three times as long as high, is set very far back, nearly twice its length from the frontal bar. A ridge extends from tooth to the third whirl. Upper tooth absent.

            Margin produced forward about as far as the diameter of the shell, is placed very nearly in the centre of the shell and is not inclined to the right, is about twice as thick as the shell behind it, is smoothly rounded on the edge and rolled over into a rather sharp edge. The frontal bar is not well-developed and does not cross the shell, being broken in the middle, hence does not completely interrupt the striations, which appear within it.

            Color of shell, externally, white, beautifully marked with longitudinal and rather continuous streaks of dark reddish brown. Internally, far within the shell, pale brown becoming white on the entire margin, tooth, and space around it, with a slight creamy tinge.

DIMENSIONS.

            Size of type, 1.12 by .45. Largest specimen, 1.12 by .47; smallest, .75 by .37. Greatest diameter, .47; smallest, .37. Longest specimen, 1.30; shortest, .97.

OBSERVATIONS.

            There is considerable individual variation, one is toward a cylin­drical form with even more numerous striations, sixty to the first whirl, with a contracted aperture, and eleven whirls. A color variation is a paler form with rather narrow markings, which are also paler. There is a tendency to produce a form with an entire frontal bar.

            There is also the following well-defined form:

            No.1. Size, very. small. Whirls, nine. Color, form and

striations as in the typical form.

            This is not the Pupa martensiana of Weinland for in that species the teeth are given as two and the margin as being thick. S. eximea may be distinguished from all other shells of this sub-genus by the large size, in the type form, and always by the dark, wide longitudinal markings. .

            There is one remarkable character in this species which is found in all the forms and one which is, as far as I have examined, peculiar to this Strophia, although I shall expect to find it occurring in others. That is a swollen ridge which, beginning back of the central tooth, winds about the column about once its width from it, thus leaving a furrow between it and the column, extends, gradually lessening in size, and it is lost in the third whirl. This ridge was once the resting place of the central tooth, and in one place, in one of the specimens

examined, a tubercle still remains on at the partition in the lower portion of the second whirl, See Fig. 61, A, being a section of a specimen of S. eximea, and the tubercle may be seen in the second whirl. This elevated ridge is no thicker than the other portion of the floor of the whirls, conse­quently has a corresponding hollow beneath. Nothing of the kind appears in the apparently closely-allied species S. agrestina, where the floor of the whirls is perfectly simple. See Fig. m, B, where I have given a section of S. agrestina. C, is a cross-section of the top whirl of S. eximea, showing the central tooth and beginning of the ridge.

HABITS AND DISTRIBUTION.

            All that I can give under this heading is the fact, that the speci­mens from which the above description was made were procured by Mr. Curtiss, in Nassau, from a creole who brought them from Cat Island.

The species is, however, not uncommon in collections, often

labelled as Pupa or Strophia martensi or martensiana."

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