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'SUBKOTUND. 



Myt. membranacea. Mat. 



Unio Maloniana. D'Orb. 



Unio subtrapezius (junior). Phili. 



Unio membranaceus. Phili. 



Variabilis. Mat. Han. D'Orb. 

 My a variabilis} Mat. Wood. Dill. 



*rotundus. Spix. Mori. 

 Diplodon rolundus. Spix. 



Fontainianus? D'Orb. HujjL 



*patelloides. Lea. 



*nocturnus. Lea. 



*gratus. Lea. 



*retusus.* Lam. Con. Menlce. Kust. 

 Han. 



Unio torsa. Eaf. Sh. & Eat. Potier. 



Chenu. 

 Unio obtusa. 3 Cuvier. 

 Unio cordatus (female). K'ust. 



*ebenus. Lea. Chenu. Han. 

 Unio mytiloides. Con.; not Raf. 

 Unio obliquus. Con. Kust. 

 Unio Gouldianus. Ward. 



SUBROTUND. 



"-Lesueurianus. Lea. Chenu. 



*Lyonii. Lea. 



*Lewisii. Lea. 



*nucleopsis. Con. 



*fibuloides. Lea. 



'^Kirtlandianus. 4 Lea. Han. 



Evansi. Ad. &• An. Peeve. 



*pilaris. Lea. Chenu. 



*dollabelloides. Lea. Chenu. 



*Thorntonii. Lea. 



*subrotundus. Lea. Chenu. Han. 

 Unio politus ? b Say. K'ust. 

 Unio brevialis? Crouch. 

 Unio politus. Con. 

 Unio cicatricosus. Peeve, Sp. 50. 



*eoccineus. 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.) 



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

 that name. 



3 In the recent edition of Cuvier Beg. An., bj' his pupils, there is a beautiful figure of U. retusus, 

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

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



4 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. 



