28 



UN 10. 



OVAL. 



spatulatus. Lea. 



*ligamentinus. Lam. 1 Kiist. 

 Unio crassus. Say. Bar. 2 



Kirtl. 

 Unio elliptieus. Bar. Hild. 

 Unio carinatus. Bar. 

 Mya gravis. Wood. 

 Unio fasciatus. Con. 3 Kiist. 



*orbiculatus. Hild. Kirtl. 

 Unio abruptus. 4 Say. Desk. 

 Unio crassus. Con. 



mid. 



australis. Lam. 

 Unio ambiguus. 



Phil. 5 

 Par. 



*Hydianus. Lea. Chenu. 

 *approximus. Lea. 

 *Claibornensis. Lea. Chenu. 



f OVAL. 



*Powellii. Lea. 



*Reeveianus. Lea. 



*luteolus. Lam. Behay. 



Unio siliquoideus. 6 Bar. Con. 



Adams. Kiist. 

 Unio inflatus. Bar. 

 Unio melinus. Con. 

 Unio rosaceus. Bekay. 

 Lampsilis siliquoidea. 7 Stimp. (Agass. 

 MSS.) 



*stramineus. Con. 



*aratus. Lea. 



Childreni. 8 Gray. 



pulcher. Lea. Chenu. 

 *tener. Lea. Chenu. 



1 Having recently had access to Retzius's work (1788), I find that he described a European Unio under the 

 name of crassus, which species had been admitted into our systems under the name of crassissimus, Fer., I now 

 restore it to its proper place under the name of crassus. 



Deshayes thinks that U ligamentinus is analogous to U. multiradiatus, and probably a young individual of it ! 

 This is not likely to be the case, however. The species are very different. 



2 Mr. Barnes made eleven varieties of crassus; most of which were, no doubt, distinct species; some were plicate. 



3 Mr. Conrad thinks the c?-assus of Say is fasciata of Rafinesque. An examination of his description ought to 

 satisfy any one that the crassus of Say could not have been under the eye of the author when he made his descrip- 

 tion of fasciata. 



* The specimen figured by Mr. Say, in Amer. Conch. No. 2, is a female shell. The male shell is not abrupt 

 at the posterior margin. 



5 Dr. Philippi figures a Unio under the name of Australis, Lam. (Tab. 5, Fig. 5), from New Holland, and 

 says that U. ambiguus, Parreyss, is the young. I did not see Lamarck's Australis, when in Paris; it was not in 

 the Museum. I very much suspect that Australis and depressus, Lam., are the same. If Philippi's figure repre- 

 sents Australis, as he believes, then I should have no further doubt. 



6 Mr. Say makes siliquoideus the same with viridis, Raf. Ferussac, in his cabinet, makes it the same with 

 fasciata, Raf. Mr. Conrad makes it the same with vittata, Raf. Ferussac, in his "Observations," states the 

 inextricable difficulty resulting from the confusion caused by Mr. Rafinesque. See "Observations," p. 13, in 

 Magazin de Zoologie. 



7 Prof. Agassiz says, in MSS. cited by Mr. Stimpson, that this is not identical with the Ohio River species 

 usually called U siliquoideus; but I think they are the same. 



6 I have never seen this species, but presume, from the figure in Griffith's Cuvier, very poor as it evidently is, 

 that it is a distinct species. In the index, Mr. Gray inserts, in brackets ( Unio Chinensis), and says it has small 

 compressed teeth. The figure looks something like a Monocondyleea, D'Orbigny. 



