U X I O . 





1, 



SUBROTUND. 



Myt. menibranacea. Mat. 



Unio Maloniana. D'Orb. 



Unio subtrapezius (junior). Phili. 



Unio membranaceus. Phili. 



*variabilis. Mat. Han. D'Orb. 

 My a variabilis. 1 Mat. Wood. Dill. 



*rotundus. Spix. Mori. 

 Diplodon rotundus. Spix. 



Fontainianus? D'Orb. Hupe. 

 *patelloides. Lea. 

 *nocturnus. Lea. 

 *gratus. Lea. 



*retusus. 2 Lam. Con. MenJce. Kust. 



Han. 

 Unio torsa. Raf. Sh. & Eat. Potier. 



Chenu. 



Unio obtusa? Cuvier. 

 Unio cordatus (female). Kust. 



*ebenus. Lea. Chenu. Han. 

 Unio mytiloides. Con.; not Raf. 

 Unio obliquus. Con. Kust. 

 Unio Oouldianus. Ward. 



SUBROTUND. 



*Lesueurianus. Lea. Chenu. 



*Lyonii. Lea. 

 *Lewisii. Lea. 

 *nucleopsis. Con. 

 *fibuloides. Lea. 

 *Kirtlandianus. 4 Lea. Han. 

 Evansi. Ad. & An. Reeve. 

 *pilaris. Lea. Chenu. 

 *dollabelloides. Lea. Chenu. 

 *Tkorntonii. Lea. 



*subrotundus. Lea. Chenu. Han. 

 Unio politus P Say. Kust. 

 Unio brevialis? Crouch. 

 Unio politus. Con. 

 Unio cicatricosus. Reeve, Sp. 50. 



*coccineus. Lea. Chenu. Han. 

 Unio coccineus. Dr. HildretKs Letter. 

 Unio coccineus. Con. 



1 The figure of this shell in the Lin. Soc. Trans., vol. x., although so much smaller a shell than 

 Paranensis (nobis), is so much like it that I should not be surprised if they should prove to be the same. 

 Lamarck considered this to be the same with his Hyria corrugata; but it is very different. 



(Since the publication of this note, I have received, from M. Moricand, a suite of specimens of 

 Paranensis, which indicate, unquestionably, a distinct species. The beaks of rotundus, Wag., have not 

 the strong folds on them, while the Paranensis has many elevated radiations from the beaks. The outline 

 too of the former is more orbicular.) 



* M. Deshayes thinks this is incurvus, Say. I do not know where Mr. Say published a shell under 

 that name. 



* In the recent edition of Cuvier Keg. An., by his pupils, there is a beautiful figure of U. retnaim, 

 Lam., under the name of U. obtusa, Say. I am not aware that Mr. Say described a Unio under that name. 

 The retusus, Lam., is a common, well-known, and perfectly distinct species. 



* Prof. Kirtland, in his Ohio Report, expresses his opinion of this being only a very flat variety of 

 subrotundus (nobis). 



6 Mr. Conrad cites Mr. Say's table of synonymy for politus, but I am not aware of Mr. S. ever 

 having described it. 



