NEW EXOTIC UNIONIDiE. 395 



Anodonta Cailliaudii. PI. 45, fig. 297. 



Testa lffivi, rotunda, ventricosa, inajquilaterali, antice superne angulata; valvulis crassis, antice aliquanto 

 crassioribus ; natibus elcvatis, tumidis, incurvis ; epidermide nigro-fusca, obsolete radiata, superne 

 ruicante, inferne exilissirne striata; margarita argentea et valde iridescente. 



Shell smooth, round, ventricose, inequilateral, angular above in front; valves 

 thick, a little thicker before ; beaks raised, swollen and incurved ; epidermis black- 

 ish-brown, obsoletely radiate, shining above and finely striate below ; nacre silver- 

 white and very iridescent. 



Hab. — Brazil, Monsieur F. Cailliaud. 



My cabinet and cabinet of M. Cailliaud. 

 Diam. 1-5, Length 2-4, Breadth 29 inches. 



Shell smooth, round, ventricose, inequilateral, angular above in front ; substance 

 of the shell thick, a little thicker before ; beaks raised, swollen and incurved ; liga- 

 ment rather short, thin and concealed ; epidermis blackish-brown, obscurely rayed, 

 very bright over the umbones and finely striate on the inferior part; umbonial 

 slope not raised, but rounded ; posterior slope broad, slightly raised, with two dark 

 and two yellow lines on each valve, from the beaks to the posterior margin ; ante- 

 rior cicatrices confluent, very large and slightly impressed ; posterior cicatrices very 

 large, confluent and very slightly impressed ; dorsal cicatrices above and within 

 the cavity of the beaks ; cavity of the shell very deep, very wide and rounded ; 

 cavity of the beaks somewhat deep and subangular ; nacre silvery-white and very 

 iridescent. 



Remarks. — I owe to the kindness of Monsieur Cailliaud the possession of a single 

 specimen of this with several other fine shells. It belongs to the same group with 

 An. rotunda, Spix, but differs in being larger, more rotund, in being much darker and 

 without strong rays. It is remarkable for its extremely regular roundness, and its 

 fine dark epidermis, which is unusually smooth and beautiful. The nacre is of most 

 uncommon brilliancy, being the purest silver-white, and is accompanied by a most 

 unusual display of iridescence. I have great pleasure in naming it after the distin- 

 guished African traveller, who has done so much to develope the natural history of 

 his own and of foreign countries. 



'-* 



Anodonta Amazonensis. PI. 46, fig. 300. 



Testa lsevi, transversa, subinflata, valde insequilaterali, postice subbiangulata, antice rotunda : valvulis 

 subcrassis ; natibus subelevatis, turnidis ; epidermide micante, tenebroso-viridi, nigricante vel era- 

 diata vel obsolete radiata ; margarita intiis subrosea et valde iridescente. 



Shell smooth, transverse, somewhat inflated, very inequilateral, somewhat bian- 

 gular behind and rounded before ; valves rather thick ; beaks somewhat raised and 



