OF SANTO DOMINGO. 



215 



OLIVA. Brug-. 



O. cylindrica. Sby. Quart. Jour. V. VI, p. 45. , , . 



0. reticularis, Lam., Guppy. Id. V. XXII, p. 288. 



After a study of nearly 600 specimens I am decidedly inclined to agree with Mr. 

 Guppy in referring- this shell to the Lamarckian species. The only ground for a 

 separation that I can discover is that the fossils are usually heavier than the recent 

 specimens and sometimes acquire a greater size. I have them 2.5 inches long. 



With these shells are two specimens isolated by their size and differing from each 

 other in such a manner .that, were they more numerous, I should be tempted to name 

 them. As it is, I dare not risk making useless synonymy. One 4: inches long has 

 a comparatively low spire and is decidedly tapering in advance; the other 3.3 inches 

 long, is cpiite high-spired and unusually slender. They arc most probably aberrant 

 forms of this species. ; • " 



O. or y z a. Lam. . 



Quite abundant and differing in no respect from recent specimens. = ■ ' ■ 



O. m u t i c o i d e s. Gabb. n. s. 



Shell elongate-ovate, spire elevated ; whorls seven ; suture deeply channeled ; inner lip encrusted with a heavy 

 callus and distinctly transversely plaited ; four or five large folds in advance extend over the end of the body whorl. 



About the size of large specimens of 0, mutica, this species is more slender, has 

 a higher spire and diffei's essentially in the inner lip. While that species has a 

 peculiar thickening, built up, as it were, on the inside margin of the lip and running 

 longitudinally on it, and has very few folds (or even none in some cases), this has no 

 such thickening, and is almost as strongly plaited as O. reticularis. 



O. gradata. Gabb, n. s. 



Shell resembling in size and shape 0. ispidula, but with a higher spire ; whorls seven ; deeply channeled ; sur- 

 face marked with a sharp offset or break in the continuity of the surface about a tenth of an inch below the channel. 

 Inner lip but lightly encrusted and marked by a few very prominent transverse folds. 



A very rare shell, but one that can be at once distinguished by the break in its 

 surface similar to but stronger than that observed in some species of Ancillaria. 



O. brevispira. Gabb, n. s. 



Shell elongate-oval, spire vei-y small, body whorl sub-cylindrical, very slightly tapering in advance, convexly 

 tapering in its upper one-third or one-fourth towards the suture ; suture clianneled ; aperture lather heavily en- 

 crusted and transversely striate by numerous small teeth ; anterior folds large. Length one to one and a-fourth 

 inches. 



Distinguishable by its comparatively slender form and by the very small spire. 



0. c a n al i cu 1 a t a. Gabb, n. s. 



Shell robust, sub-cylindrical, spire moderately elevated, deeply channeled ; whorls seven or eight. Aperture 

 linear ; inner lip heavily encrusted, crossed by numerous fine transverse strias ; internal surface excavated (by absorp- 

 tion) so as to produce an angulated ridge. Length .8 inch. 



IN^earest to O. jimbriata ivom v^lnch- it can be at once distinguished by its moi'e 

 cylindrical form, lower spire nnd entirely ditl'ei-ent aperture. 



