274 SUBEMARGINULA. 



Shell oval, conical ; front margin not notched ; apex subcentral, 

 inclined backward and to the right side ; front slope convex, back 

 slope straight ; sculptured with strong radiating ribs of which 8 at 

 equal distances are larger, extending from apex to basal margin, 8 

 shorter secondary ribs, and on large specimens still smaller tertiary 

 riblets. All of these are rudely nodulose. Color white or greenish 

 outside. Interior olive-green (or sage-green), white in the center and 

 around the margins. Anterior groove narrow, rather deep. Margin 

 coarsely dentate. Length 24, breadth 20, alt. 10 mill. 



Tortugas to Barbados, Nicaragua and Aspinwall. 



Patella ocloradiata (in part) Gmel., Syst. Nat. xiii, p. 3699. — 

 Subemarginula octoradiata A. Ad., P. Z. S. 1851, p. 90, founding 

 Gmelin's species upon " Patella alba, panels et valde eminentibus 

 striis stellata" Lister, t. 532, f. 11 (Barbados). — Emarginula octo- 

 radiata Gin., Arango, Faun. Mai. Cub. p. 229. — Dall, Catal. Mar. 

 Moll. S. E. U. S. p. 170.— Emarginula tricostata Sowb.. Genera, f. 

 6 (inside only figured, scarcely recognizable). — E. tricostata Sowb., 

 Reeve, Conch. Syst. p. 23, t. 140, f. 5, 6, good! — E. depressa 

 " Blainville," Sowb., Con oh. Icon. f. 3 and again, f. 55. — IE. guada- 

 loupensis Sowb. 2d, Thes. p. 219, f. 69; Conch. Icon. f. 60. — E. 

 clausa Orb., in Sagra, Moll. Cuba, p. 269, t, 24, f. 34-36.— E. 

 laqueare Gray and E. listeri Anton, teste Arango, on authority of 

 Dunker. 



Gmelin's description applies fairly well to this species, but his 

 references are all at sea. In accepting Arthur Adams' first identi- 

 fication (1851), taking Lister's fig. 11, pi. 532 as the type, we are 

 adopting the course pursued by most writers on the West Indian 

 fauna. This is the E. depressa of Sowerby 2d. (pi. 29, figs. 17, 18), 

 not of Blainville. A wise malacologist will decline to say what E. 

 depressa Blainv. (Malacol., p. 501, t. 48bis. f. 2) may be ; from its 

 toad-stool shaped central area I would consider it an oriental form. 



This is a well-known West Indian species having eight strong 

 primary ribs, and intervening shorter ones. The ribs have no 

 tendericy to be double, or bifurcate, a diagnostic point of great value. 



S. rollandii Fischer. PL 64, fig. 36. 



Shell small, oval, apex subcentral, anterior fissure about three 

 times as long as wide ; front slope convex, back slope straight or 

 concave. Sculptured with unequal radiating riblets, very variable 

 in number (22-28) ; ribs irregularly beaded, the interstices bearing 



