26 AMERICAN CORBICULAD^!. 



shape and bulk; it differs, however, in being very much less heavy 

 and solid ; the hinge-margin is narrower and the teeth are smaller 

 and slighter. 



24. Cyrena tumida, PRIME. Shell trigonal, inflated, equilateral, 

 somewhat solid ; anterior margin convex, obtuse, subangular ; posterior 

 margin convex, presenting a declivity on the upper part, angular, sub- 

 rostrated ; inferior margin ventricose ; epidermis dark ; &quot;beaks very small, 

 depressed, opposite ; hinge-margin narrow ; cardinal teeth small, narrow, 

 the two larger ones bifid ; lateral teeth unequal, compressed, the anterior 

 one large, acute, triangular ; valves white in the interior with a rosy hue. 



Long. 1.36; Lat. 1.20 ; Diam. 0.80 inches. 

 &quot; 34; &quot; 30; &quot; 20 mill. 



Hob. Central America. (Cabinet of Cuming.) 



Cyrena angulata, DESH. (preoc.) Proc. Zool. XXII, 1854, 22. 



The only specimen I have seen of this species is the one in the 

 collection of Mr. Cuming. 



25. Cyrena pullastra, MORCH. C. testa ovalis, tennis, albescens, 

 radiatirn subtilissime striata, valde inaequilateralis, convexiuscula, antice 

 brevissime angustata, ppstice late rotuudata, margo dorsalis anticus preci- 

 pite declivis, posticus rectus fere horizontalis, postice angulo obtuso ; 

 margo ventralis parum arcuatus ; area postice violacea tincta ; dens late- 

 ralis posticus valvse sinistrse remotissimus, compressus, inter laminas 2 

 valvse dextrse receptus ; dens anticus subapproximatus ; sinus syphonalis 

 angustissimus, sursum spectans. 



Long. 30 ; Lat. 23 mill. 



Hab. Central America, at Realejo in Nicaragua. (Cabinet of Morch.) 

 Cyrena (Polymesoda) pullastra, MORCH, Malak. Bl. VII, 1860, 194.) 



I have not been able to identify this species. I know of no 

 Cyrena from Realejo to which the above description would apply. 



26. Cyrena inflata, PHILIPPI. C. testa ovato-trigona, valde tu 

 mida, tenui, irregulariter transversirn striata, epidermide olivaceo-nigres- 

 cente vestita ; extremitate postica elongata ; apice subtruncata ; margine 

 ventrali parum arcuato ; apicibus valde prominentibus, involutis, decorti- 

 catis ; dentibus cardinis lateralibus integris, in valva dextra abrupte ter~ 

 luinatis ; paging, interim alba. 



Long. 28}- &quot;; Alt. 26}&quot; ; Crass. 21 J&quot; . 



Hab. Central America, in Costa Rica. (Cabinet of v. d. Busch.) 

 Cijrcna inflata, PHILIPPI, Zeit. Malak. 1851, 71. 



