"STROPHIA EBURNIA Novo.

Ivory Strophia.

FIG. 45, A, front view, B, side view of type.

DESCRIPTION.

            SP. CH. Size rather small. Shell, quite thick. Striations,

present. Whirls, ten. Examined, 100 specimens.

            Form of shell, an elongated cylinder with the first three whirls about equal in diameter, the fourth is but little smaller, then the shell slopes to a rather acute point, forming an angle of sixty-five degrees.

            The striations are quite nnmerous, twenty-five to the first whirl, are not prominent, quite regular, but not arranged in lines. All are considerably inclined from right to left, they are smoothly rounded and polished, and a little more than one half as wide as the inter­spaces between them.

            Aperture, rather small, but quite open, and not at all contracted at the entrance. Lower tooth, rather prominent, a little elevated, about .03 high, and about three times as long as high. There is a slight tubercle on the left side between it and the upper tooth. The upper tooth is also well developed, and extends further forward than is usual, while the space between it and the tubercle is inclined to be filled in.

            Margin, not produced as far forward as the diameter of the shell, and is placed more nearly central in the shell than is usual, and does not incline at all to the right, it is a little thickened, with the edges beveled and produced backward into a blunt edge. The frontal bar is not well developed, but completely interrupts the stria­tions.

            Color of shell, externally, ivory white, with a faint bluish tinge, as is plainly noticeable in the sutures between the whirls; within it is pale brown, which color extends over

the teeth very nearly to the edge of the margin before fading into creamy white.

DIMENSIONS.

            Size of type, 1.15 by .45. Largest specimen, 1.32 by .47; smallest, 1.00 by .45. Greatest diameter, .48; smallest, .42. Longest specimen, 1.47; shortest, 1.03.     .

OBSERVATIONS.

            Individual variation in this well-marked and peculiar species is in two ways, as follows:  

            One is towards a larger, more pointed form and another towards one which is shorter. The tubercle on the left side of the central tooth is peculiar and marks a tendency which in some specimens becomes very prominent and forms a decided double tooth. With this double tooth, which appears in about one half the specimens examined, which were unfavorable to the Strophias, so. they gradually died.

            The remains were scattered quite regularly over the entire surface of the key, but, judging from specimens examined, they remained alive longest in the southern portion of the islet near the site of the Indian well, of which I have spoken."