10 



Unio ?lanicostatus. — Testa laevi, elliptica, compressa, ad latere subplanulata, 

 valde intequilaterali, postiee obtuse biangulata ; antice rotundata; valvulis 

 tenuibus, diaphanis, antice paulisper crassioribus: natibus prominulis, ad apices 

 uadulatis ; epidermide olivacea, undique radiata ; dentibus cardinalibus par- 

 via, conieis, crenulatis, ia utroque valvulo duplicibus; lateralibus longis lamel- 

 latis subcurvisque ; margarita vel caeruleo-alba vel purpurascente et valde 

 irrdescente. 



Rah. — Tuscumbia, Alabama, L. B. Thornton, Esq. 



Unio scitulcs. — Testfi, laevi, elliptica, inflata, valde inaequilaterali, postiee 

 obtuse biangulata, antice rotundata ; valvulis subtenuibus, antice crassioribus ; 

 natibus prominentibus, ad apices undulatis ; epidermide lutea, undique virido- 

 radiata ; dentibus cardinalibus parviusculis, erectis, acuminatis, crenulatis, in 

 utroque valvulo duplicibus ; lateralibus longis, lamellatis subrectisque ; mar- 

 uarita alba et valde iridescente. 



Hab. — Tuscumbia, Alabama, L. B. Thornton, Esq. 



f Communicated April 10th, I860.] 



Mr. Lea remarked that he had recently received from Prof. J. Wynian 

 specimens in alcohol of two species of Anodonta from the Uruguay River, 

 South America, descriptions of the soft parts of which he had made, and in- 

 tended, at a future time, to publish in the Journal at length ; but he wished 

 at present to mention that he had found a form of Palpi (mouth lips) different 

 from any of the Unionidce which had come under his notice from any other 

 part of the world. The form of the Palpi heretofore described have always 

 been obliquely or transversely elliptical or subtriangular, while these two spe- 

 cies, An. Wymanii, Lea, unAAn. lato-marginata, Lea, are round, and the pair on 

 either side only joined above, the edges being entirely free. It is greatly to 

 be regretted that more or all the South American Unionidce could not have 

 been examined, as regards their soft parts, to ascertain if this difference of 

 form of the Palpi should be persistently different in all the South American 

 Unionidce, or only with this member of the family — the Anodontoz. 



