OF SANTO DOMIN^GO. 



243 



C. pen tag on a. Gabb, ii. s. 



Shell minute, discoidal, spire moderately elevated ; umbilicus perspective ; wliorls five, cross section rudely 

 pentagonal, flat on top, witli three keels on the outer surface, one at the upper and one at the lower angle, and the 

 third in the middle ; the umbilical margin is faintly angulated ; except these keels the surface is polished, and with- 

 out ornament. 



ADEORBIS. S. Wood. 



A. c a r i n a t a. Gabb, u. s. 



Shell depressed trochiform, whorls five, rounded above and below with a prominent raised keel in the middle ; 

 umbilicus narrow, perspective, margin faintly angulated ; apertui'e elliptical, outer lip produced into a short tongue- 

 like angle in the middle at the end of the rib. 



A peculiar little shell, of which the whorls are a little broader than high, and bear 

 a keel in the middle. This is visible only on the body whorl, being coincident with 

 the suture in the upper volutions. This may be the shell figured by d'Orbigny (La 

 Sagra, pi. 18, fig. 26-28) as Rotella carinata, but its opep umbilicus forbids the 

 reference to that genus or even the family. It is clearly an Adeorhis. , 



UMBONIUM. Link. 



U. vitreuni. Gabbj n. s. 



Shell minute, vitreous, spire moderately elevated, whorls three, round, sutural edge slightly thickened, surface 

 polished, mouth round, inner lip thickened and slightly expanded ; callus narrow, surface polished. 



JSTearest to U. semistriatum, d'Orb. (La Sagra, Cuba, pi. 18, fig. 20-22), but with 

 a higher spire, rounder mouth, and without the striae of that species. 



CALLIOSTOMA. Swains. 



C. c o n i c a. Gabb, n. s. 



Shell small, conical, spire high, whorls numerous, sides flattened, so that there is an iminterrupted straight line 

 from the apex to base of the body whorl ; sides ornamented by about seven simple, rounded, revolving ribs with 

 narrow interspaces ; base covered with ribs smaller than those above. Aperture sub-quadrate. 



My single specimen may be young. It is .25 inch in height, but its characters 

 are different from any other species I know. It is nearest C. zizyplihius, but differs 

 in the much narrower apical angle and in the uniform size of all of the ribs, wanting 

 the characteristic large rib on the angle. In shape it is very near to G. jujubinus. 



OMPHALIUS. Philippi. 



O. V i r i d u 1 u s. Gruel, sp. 

 Trochus, id. Gruel., p. 3574. 



0. virichdus. H. and A. Ad. Geo., P. P. Carp. Mozat. Moll. p. 334. 



I have compared the specimens with authentic West Coast shells, and find them 

 identical in all their details. 



MARGARITA. Leach. 



M. tricarinata. Gabb, n. s. 



Shell minute, spire elevated, whorls three or foni-, the upper ones rounded, body whorl bearing three strong 

 carinations, top of the whorl bearing one or two ribs, and crenulated adjoining the suture, base slightly convex, 

 iimbilicus large, margin bordered by a crenulated rib. Aperture rounded, simple. 



A very minute shell, about equal in size to Cyclops depressus and Un\T)onium 

 vitreum, at once distinguished by its high spire, open umbilicus, and tricarinated 

 whorls. 



