rxio. 



41 



■r. 



W 



o 



y. 

 P 



H 



E- 



o 



a 

 p. 



>< 



CO 



g 



O 



OBLIQUE. 



f/i/rt gibbosus. Co7l. 

 Unio perobliquus. Con. 



*Haysianus. 1 Lea. Han. 



*ellipsis. 3 Lea. Say. Sh. & Eat. Po- 

 tter. Chenu. Han. 



Unio brevialisf Sow. 



*crapulus. Lea. 

 *Higginsii. Lea. 

 *castaneus. Lea. Chenu. Han. 

 *Johannis. Lea. 

 . *Gentb.ii. Lea. 



*pulvinulus. Lea. 

 *modicellus. Lea. 

 *Arkansasensis. Lea. 



OVAL. 



*Tampicoensis. Lea. Chenu. Han. 



*Coloradoensis. Lea. 



*umbrosus. Lea. 



*porphyreus. Lea. 



'OVAL. 



Thwaitesii. Lea. BJan. 



*Lecontiamis. Lea. Chenu. Han. 

 Unio conlrarius. Con. 



*spissus. Lea. 



*Downiei. Lea. 



*Satillaensis. Lea. 



*geraiuus. Lea. 



*perdix. Lea. Han. 



Unio pectorosus. Con. Kiist. 



* ventricosus. Bar. Adams. Del-ay. 



Han. 

 Unio radiatus. Hill. 

 Lampsilis ventricosa. Stimp. (Agass. 



MSS.) 

 Mya ventricosa. Eat. 



*occidens. 3 Lea. Sh. <£• Eat. Han. 

 Unio ventricosus. Say. 

 Unio lenis (junior). Con, 

 Unio cardium. Con. 



*lineatus. Lea. Chenu. 



*dolabrseformis. Lea. Chenu. Han. 



1 I am very much disposed to think that Eaijsianus will prove to be the female of Sowerbianus (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. 



2 Mr. Say, in his American Conchology, refigures this, and recognizes my name. Subsequently, in 

 his Synonymy, he makes it a synonym of triangularis, Raf. Mr. Conrad says it is olivarius, Raf. 



3 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 thinks they are male and female. Subsequent examination 

 may throw sufficient light upon them to decide with certainty. 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, subovatus, &c. 



11 



