40 



UNIO. 



g 



OBLIQUE. 



*bulbosus. Lea. 



*IIanleyianus. Lea. 

 *flavidulus. Lea. 

 *pallidofulvus. Lea. 

 *interventus. Lea. 



*decisus. Lea. Con. Kilst. Chenu. 

 Han. 



*crebrivittatus. Lea. 

 *consanguineus. Lea. 

 *Cliattanoogaensis. Lea. 

 *anaticulus. Lea. Reeve* 

 *curtus. Lea. 



*clavus. Lam. Con. Menke. Kilst. 



Han. 



Unio scalenia. Raf. 

 Unio modioliformis. Say; not of Lea. 



*patulus. Lea. Con. Desk. Chenu. 

 Han. 



*Lesleyi. Lea. 

 *mundus. Lea. 



OBLIQUE. 



*Murrayensis. Lea. 

 *oviformis. Con. 

 *argenteus. Lea. Chenu. 

 *pyriformis. Lea. 

 *castus. Lea. 



*Kaveneliamis. Lea. Han. 

 Unio rudis. Con. 



ravistellus. More. 

 *modicus. Lea. 

 *Trosclielianus. Lea. 

 *medius. Lea. 

 *striatus. Lea. 



*Eangianus. 2 Lea. Chenu. Han. 

 Unio gMosus. Kiist. (PI. 4, Fig. 4.) 



*Sampsonii. Lea. 



*sulcatus. Lea. Sh, & Eat. Say. Desk. 



Chenu. Swain. Han. 

 Unio ridibundus. Say. Sh. & Eat. 



(Female.) 3 

 Unio pectitus.* Con. Jl. A. N. S., 



vol. 2, p. 297.) 



1 I doubt if the figure of Reeve (199) be made from a true anaticulus. 



2 This species has been supposed by some naturalists to be the same with perplexus (nobis). Mr. 

 Clark, of Cincinnati, informs me that the animal differs in color, being lighter. It is known there 

 A r ulgarly as the "White Mouth." They are certainly distinct species. 



3 For some years, I was satisfied that Mr. Say's ridibundus was only a variety of sulcatns (nobis). 

 There cannot now, however, be a doubt that it is the female of that species ; and it may be remarked 

 that this serrated shell is usually found smaller than the other ; a circumstance common with the females 

 of some other species. Mr. S. describes and figures ridibundus in No. 1 of American Conchology, but 

 does not insert it in his Synonymy, in Xo. 6. 



4 Mr. Conrad described and figured a male and female shell from the Wabash under this name. 

 There is no doubt in my mind of their being the same with sulcatus, Lea (male), and ridibundus, Say 

 (female). Mr. C. thinks this species has some analogy to lenior, Lea, but it has not the same outline, 

 and differs in other characters. He thinks the males have been "confounded with that of torulosus, Raf.;" 

 but what is torulosus, Raf.? Mr. C. considers it, in his Synonymy, the same with perplexus, Lea. Mr. 

 Say, however, discards torulosus, Raf., and considers perplexus, Lea, as a synonym to gibboaus, Raf. 

 Mr. C.'s figure of metastriatus is much more like lenior, Lea. 



