78 



terior basal portion prove constant, there can be no room for 

 doubt. 



Osteodesma Brasiliensis (Couthouy, MS.) Testa fragilis, 

 elongato-ovata, antice ventricosa et truncata, postice compressa, 

 concentrice undulata, epidermide flavicante induta ; umbonibus 

 ante-medianis, tumidis, approximatis ; rnargine dorsuli fere rec- 

 tilineari ; margine ventrali arcuato: interior margaritacea : ossi- 

 culum parvum, oblongum. Long. l£ ; alt. £ poll. Hab. Rio 

 Janeiro. 



Its elongated, leguminous form, and its large size, plainly 

 characterize it. 



Amphidesma croceum. Testa maxima, crassa, calcarea, ine- 

 quivalvis, subcircularis, postice hiantula et sub-truncata, liris 

 concentricis reflexis intcrdum divaricatis arata, radiatim stri- 

 ata; umbonibus sub-medianis, emincntibus, acutis, contiguis : 

 intus crocea; cardo validus, fovea ligamentali ampla, profunda ; 

 dentibus rosaceis. Long. 3£; alt. 3£ ; lat. 1£ poll. Hab. 

 Callao? 



Very distinct from all other described species, unless it may 

 be A. solidum, Gray ; from comparison with his description 

 alone, this must be different. 



Erycina (Poronia) ovata. T. parva, alba, nitida, concen- 

 trice striata, ovato-ventricosa, inequilateralis ; margine cardinali 

 arcuata, umbonibus parvis, antemedianis; margine ventrali parum 

 arcuata; latere antico truncato ; latere postico rotundato ; valvse 

 dextrse dente cardinali erecto, bifido, fovea ligamentali parva ; 

 v. s. dente integro ; intus alba. Long. ^ ; alt. \ ; lat. \ poll. 

 Hab. Sandwich Islands. 



Differs from the succeeding species in its smaller size, more 

 inequilateral, ovate-ventricose form, shining surface, and delicate 

 hinge. 



Erycina (Kellia) quadrata. Testa parva, tenuis, ventri- 

 cosa, ad angulos rotundata, concentrice et concinne striata, epi- 

 dermide straminea induta ; umbonibus fere medianis, tumidis, 

 anteversis : area cardinalis ampliata, in valva sinistra tridentata 

 (dente mediano subulato, sub umbone sito; alteris elongatis, com- 

 pressis) in valva dextra bidentata ; fossa ligamentali triangulari, 

 declivi. Long. £ ; alt. f ; lat. £ poll. Hab. Feejee Islands ? 



