APPENDIX. 



&quot;T 7 . Corbicula perplexa. PRIME. Testa transversa, ovato-sub- 

 trigona, insequilaterali, compressa ; latere antico breviore, rotundato ; trans- 

 versim dense et irregulariter striata ; epidermide squalide 

 virescente vestita. Fig. 84. 



Shell transverse, oval, subtrigonal, inequilateral, com 

 pressed ; anterior side shorter, rounded ; posterior side some 

 what narrower at extremity ; valves moderately solid, interior 

 purplish-white with purple markings under the posterior 

 lateral tooth and with distant and more or less distinct purple 

 lines radiating from the apex of the shell towards the basal perplexa. 

 margin ; striae very close, irregular and indistinct ; epidermis 

 of a soiled green ; beaks small, somewhat raised ; hinge-margin broad 

 with three unequal diverging cardinal teeth, the principal ones bifurcated ; 

 anterior cardinal tooth in the right valve nearly obsolete ; palleal im 

 pression terminating in a small and short sinus. 

 Long. .48 ; Lat. .40 inch. 

 &quot; 12; 10 mill. 



Eab. South America. (Cabinet of Prime.) 



This species is very closely allied to Corb. limosa; it is how 

 ever much smaller, more transverse, more produced on the 

 posterior side ; the hinge is less solid, and the cavity of the valves 

 is deeper. I have failed to discover in any specimens of Corb. 

 perplexa the radiating colored lines, which are frequently met 

 with on the epidermis of Corb. limosa. 



15 . Pisidium ultramoiitaimm, PRIME. Testa ovato-sub- 

 orbiculari, subinsequilaterali, compressa, solidiuscula ; 

 umbonibus parvis, subdepressis, parum prominulis. Fig. 85. 



Shell comparatively solid, oval-suborbicular, subinequi- 

 lateral, compressed ; anterior side much produced between 

 the extremity of the lateral tooth and the junction with 

 the basal margin ; posterior margin rounded ; beaks small, 

 *not full, not much raised above the outline of the shell ; 

 valves shallow in the cavity ; hinge strong ; striae delicate ; Pisidium 



epidermis light brownish horn color. ultramontanum. 



( 7ft) 



