378 CALLIOSTOMA. 



most of which, like a twisted cable, forms a sort of pillar with a 

 chink between it and the sharp edge of the pillar-lip, and advances 

 into a small tooth at the angle where it joins the outer lip on the 

 base. Longitudinals the whole surface is roughened by rather 

 coarse oblique lines of growth, which on the upper whorls appear 

 as oblique, reticulating ribs. Color white, with a translucent cal- 

 careous layer over nacre. Spire rather high, scalar. Apex a little 

 flattened down and rounded, the minute rounded embryonic 1 1 

 Avhorls scarcely rising above the level. Whorls 6, of rather rapid 

 increase, with a narrow flat shelf below the suture, thence sloping 

 flatly to the shoulder-carina, from which point the contour-line 

 descends perpendicularly ; the base is inflated at the edge and 

 flattened in the middle. Suture deeply impressed between the 

 narrow flat shelf below and the over hanging carina above. Mouth 

 slightly oblique, but with a perpendicular pillar, round, nacreous 

 within. Outer lip thin, transparently porcelaneous on the edge, but 

 thickened by nacre within. Pillar-lip perpendicular, rounded within 

 the mouth, advancing to a sharp point in front, slightly reverted 

 but not appressed, having a small open furrow and a minute um- 

 bilical chink behind it. (Watson.) Alt. '3 in., diam. '26 inch. 



Off Culebra Island, West Indies, in 390 fms. 



Trochus (Ziziphinus) stirophorus WATSON, ' Challenger ' Gasterop. 

 Eep., p. 59, t. 6, f. 2 ; Journ. Linn. Soc. London xiv, p. 695. 



Ihis species extremely resembles Trochus ocddentalis Migh., but 

 is smaller, is broader in proportion, with a less high spire ; the 

 apex is not sharp and projecting, but flattened down and rounded ; 

 the whorls are much more scalar, and of more rapid increase ; the 

 base is more tumid on its outer edge and more rounded. The apex 

 is ornamented with a microscopic and quite irregular inlaid work of 

 angular depressions, parted by very narrow r interrupted raised lines ; 

 whereas in that species the ornamentation is like honeycomb, with 

 relatively large, nearly regular hexagonal pits and raised flat 

 borders. The threads on the base are approximate, not parted in 

 the middle by a smooth zone, and the pillar-lip is not appressed as 

 in that species ; the outer lip, too, is thickened within by the layer 

 of nacre. ( Watson.) 



C. SAPIDUM Dall. PI. 49, figs. 38, 39. 



This species bears a strong superficial resemblance to the last 

 [apieinum] and is best described by a differential diagnosis ; it is 



