352 DESCRIPTIONS OP NEW SPECIES OF FOSSILS 



Figure. Magnified seven times linear. 



From near Moen. 



From M. elevata, G., Sto. Domingo (fig. 36), of which I give a figure for com- 

 parison, it can be distinguished by its more slender form, flatter sides, much nar- 

 rower and deeper sinus, and by a peculiar difference in the style of the revolving 

 ribs, hard to describe, but very evident when the two shells are placed side by side. 

 In this the ribs look rougher, they are more numerous and more elevated. In the 

 Dominican shell the appearance is rather that of a flat surface on which the ribs 

 are laid. I long considered them the same, but close comparison constrained me 

 to separate them, though perhaps a larger series would again throw them together. 



M. LATA, Gabb, n. s., PI. 46, fig. 37. 



Shell small, robust, broad, spire elevated; number of whorls unknown. Whorls 

 convex on the sides, body whorl tapering rapidly and sinuously in front ; suture 

 well marked, the top of each whorl rounding in abruptly. Surface marked by 

 about eight slightly sinuous longitudinal ribs with broader concave interspaces. 

 No intermediate sculpture or minute markings of any kind, except half a dozen 

 revolving grooves on the extreme anterior end of the body whorl. 



Figure. Magnified between four and five times. 



A plain shell with a smooth polished surface, relieved by the large undulating 

 ribs. It is principally remarkable for being the most robust species of the genus 

 yet found in the Caribbean Tertiaries. In size and shape this is near to M. 

 Q'Pleurot.") Auberiana, d'Orb., La Sagra, pi. 25, f. 4-6, but the ribs are more 

 oblique, and this wants the spiral sculpture of that species. I have but a single 

 specimen in which the mouth and whole adjoining surface were apparently injured 

 before fossilization, and then encrusted with parasites. But the surface figured is 

 in good preservation. 



From Moen. 



TRITONIUM, Link. 

 T. TRiTONis, Linn. sp. 



This well-known shell is represented by a young specimen barely three inches 

 long, and by a perfectly recognizable fragment of another that must have been a 

 foot long when perfect. Both retain traces of color. 



T. (cymatium) pemorale, Linn. sp. Lam., A. S. Y., v. 9, p. 632. 

 A couple of fine specimens. 



T. (lampusia) lineatum, Brod., P. Z. S., 1833, p. 6. 



Fossil in the Miocene of Santo Domingo, here again in the Pliocene between 



