UNIO. 



41 



OBLIQUE. 



Unio giblosus. Con. 

 Unio perolliquus. Con, 



*Haysianus.^ Lea. Han, 



*ellipsis.^ Lea. Say. Sh. & Eat. Po- 

 tter. Chenu. Han. 

 TJnio hrevialisf Sow. 



*crapulus. Lea. 



*Higginsii. Lea, 



*castaneus. Lea. Chenu. Han. 



*Jo]iannis. Lea. 



. *Gentliii. Lea. 



*pulvinulus. Lea. 



*modicellus. Lea. 



*Ar]iaiisaseiisis. Lea. 



OVAL. 



*Tampicoensis. Lea. Chenu. Han. 



*ColoracToensis. Lea. 



"umbrosus. Lea. 



""porpliyreus. Lea. 



( OVAL. , 



Thwaitesii. Lea. Blan. 



*Lecontianus. Lea. Chenu. Han. 

 Unio contrarius. Con. 



*spissus. Lea. 



*Downiei. Lea. 



*Satillaensis. Lea. 



*gemmxis. Lea. 



*perdix. Lea. Han. 



Unio pectorosus. Con. Kust. 



"ventricosus. Bar. Adams. Dehay. 

 Han. 

 Unio racliatus. Hilcl. 

 Lampsilis ventricosa. Stimp. (Agass. 



■MSS.) 

 Mya ve7itricosa. Hat. 



*occidens.^ Lea. Sh. & Eat. Han, 

 Unio ventricosus. Say. 

 Unio lenis (jtmior). Con. 

 Unio cardiicm. Con. 



*lineat'us. Lea. Chenu. 



""dolabr£eforniis. Lea. Chenu. Han. 



' I am very nmch disposed to think that Maysianus will prove to be the female of Soiverhianus (nobis). 

 They differ much in size, but in other characters are much alike, except in the female enlargement. The 

 latter is the larger, and has never, so far as I know, been found with charged branchial uteri. The former 

 usually has them charged, I am informed. 



^ Mr. Say, in his American Conchology, reflgures this, and recognizes my name. Subsequently, in 

 his Synonymy, he makes it a synonym of triangulai-is, Raf. Mr. Conrad sa3^s it is olivarius, Raf. 



=" This and the preceding shell are so nearly allied, that it is a matter of doubt with me if it would 

 not be preferable to unite them. Dr. Ward thiuks they are male and female. Subsequent examination 

 may throw sufficient light upon them to decide with certaintj''. Among Mr. Barnes's varieties of ventri- 

 cosus, it is evident there are several distinct species. Prof. Kirtland, in Ohio Reports, says it is impos- 

 sible, with our present knowledge, to draw lines of specific distinction between the group consisting of 

 ovatus, ventricosus, occidens, siibovatus, &c. 

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