CORBICULA. 7 



scription was prepared, authentic Corb. incrassata, Desh., ob 

 tained from Mr. Cuming, from whose collection Mr. Deshayes 

 described this species, are identical with it. 



7. CorMciila bras il Ian a, DESHAYES. C. testa trigona, subtrans- 

 versa, tumid ula, insequilaterali, tenue et regulariter transversim striata, 

 epiderinide viridi niteute vestita ; unibonibus iniuimis, proininulis, oppo- 

 bitis ; latere antico paulo breviori, superne rectilineo, declivi, postico pa- 

 rumper atteiiuato, rotundato ; cardine angusto tridentato, altero bideutato, 

 dentibus rniniinis divergeutibus, lateralibus elongatis, angustis, sub lente 

 exilime striatis ; sinu pallii parvulo triangular!, apice acutissimo. 



Hob. South America, at Para, iu Brazil. (Cabinet of the British Mu 

 seum.) 



Corbicula brasiliana, DESHAYES, Biv. Brit. Mus. 1854, 232. 



I have not seen any specimens of this species. 



FOSSIL SPECIES. 



8. CorMcula truncata, PRIME. C. testa cordata, inaequilatera, 

 oblique truncata ; sulcis transversis, latere antico- angulato. 



Long. .25 mill. 



Hob. North America; (in the State of New York?). (Cabinets of the 

 Garden of Plants in Paris and of Valenciennes.) 



Cyrena truncata LAMARCK, Aiiim. s. vert. V, 1818, 553. 



I have never seen this species, which I am inclined to believe 

 does not come from New York, but more probably from some of 

 the Southern States. Mr. Deshayes says in the Encyclopedic 

 Me thodique, that it bears such a close resemblance to Cyrena 

 cuneiformis, that some of the valves of the two species actually 

 titted into each other. 



9. Corbicula moreauensis, MEEK and HAYDEN. &quot;Shell ovate, 

 nearly elliptical, compressed, extremities rounded ; anterior end narrower 

 than the posterior, base semi-ovate, most prominent behind the middle ; 

 beaks not much elevated, placed a little in advance of the centre ; surface 

 marked with fine distinct lines of growth; cardinal edge rather thick, and 

 having under the beaks three diverging central teeth in each valve, the 

 anterior of which is the smallest ; lateral teeth two (in the left valve) 

 long, parallel to the cardinal edge, and fitting into corresponding grooves 

 in the other valve; muscular impressions deep.&quot; 



Long. 0.90; Lat. 0.66 ; Diam. 0.36 inch. 



Hob. North America, near Moreau River, Nebraska. Tertiary forma 

 tion. (Cabinet of the Smithsonian Institution.) 



