276 SUBEMARGINULA. 



S. EMARGINATA Blainville. PL 64, figs. 3, 24, 25, 26. 



Shell oblong, elevated, apex recurved, subcentral ; principal ribs 

 10, three front ones prominent, stout, double ; white outside and in- 

 side. 



The surface is strongly, coarsely latticed by elevated concentric 

 cords or lamellae crossing the radiating ribs. Of the latter, three 

 front ones are prominent, the middle one elevated, the two side-ribs 

 double ; there are three riblets in each interval between the 10 

 primary ribs, sometimes more by the intercalation of minute ones; 

 color white or yellowisjh ; interior white ; anterior groove distinct, 

 ending in a slight notch. Margins irregularly denticulate, 30-35 

 denticles (large and small) in all. Ends elevated, so that the shell 

 rests upon the side-margins alone, when placed upon a plane surface. 



Length 25, breadth 14, alt. 13 mill. 



Length 23, breadth 16, alt. 10 mill. 



Florida Keys; St. Thomas. 



Emarginula emarginata BLAINV. Malacol., p. 501, t. 48 bis., f. 3, 

 1825. REEVE, Conch. Syst., p. 23, t. 140, f. 4. 



This large species is allied to E. tricarinata, but is thinner, more ir- 

 regular in form, and pure white inside. 



The E. guadaloupensis of Sowerby (pi. 29, fig. 37) may be a 

 synonym of this species rather than of octoradiata. 



S. ALVEOLATA A. Adams. PI. 29, figs. 12, 13. 



Shell thin, white, subpellucid, depressed-conical ; vertex subcen- 

 tral, inclined backward ; irregularly alveolate by radiating ribs and 

 transverse lirse ; ribs nodulose at the intersections of the line ; pits 

 pellucid ; margin of the aperture dentate, sinuated in front, sinus 

 produced into a canal within. (Ad.} 



Honduras. 



Subemarg. alveolata AD., P. Z. S. 1851, p. 90. Sown., Thes. p. 

 218, f. 82, 83 ; Conch. Icon. f. 51. 



The figures given by Sowerby do not agree very well with the 

 words vertice subcentrali of Adams' description. 



Indo-Pacific species. 



S. TRICARINATA Born. PI. 29, figs. 7, 8, 9. 



Shell an elevated recurved cone ; three anterior ribs stout and 

 prominent ; interior bright green. 



