22 



SYNOPSIS OF 



Xf} 



H 



O 

 I— ( 



w 

 o 

 >^ 



I 



O 



o ' 



OBLIQUE. 



clavus. Lam. Con. 

 Unio scalenia. ^«/^ 

 Unio modioliformis. Say; not of Z.ea. 



patulus. Lea. 



Ravenelianus.* Lea. 



sulcatus. Lea. Eat. Say. 



Unio ridibundus. Say. Eat. (Female.t) 



Haysianus. Lea. 



ellipsis.^ Lea. Eat. 



castaneus. Lea. 



OVAL. 



Tampicoensis. Lea. 



* Mr. Conrad has subsequently published a different species under this 

 name. 



+ For some years I was satisfied that Mr. Say's ridibrtndiis was only a 

 variety of sulcatus, (nobis.) There cannot now, however, scarcely be a 

 doubt but that it is the female of that species; but it must be remarked, that 

 this serrated shell is usually found smaller than the other; a circumstance not 

 common with the females of other species. Mr. S. describes and figures ridi- 

 bundus in No. 1 of " American Conchology," but does not insert it in his 

 " Synonymy" in No. 6. 



^ Mr. Say, in his " American Conchology," refigurcs this, and recognizes 

 my name. Subsequently, in his " Synonymy," he makes it a synonym of 

 triangularis, Raf. Mr. Conrad says it is oUvarius, Raf. 



