18 



SYNOPSIS OP 



m 



H 

 Z 

 O 



I— I 



z 

 & 



O , 



CL, 



o 



f fOBLIQUE. 



*Tioostensis. Lea. 

 Uuio tiabalis. Con. 



* Tigris. Fer. 



*Taitianus. Lea. 



cor. Con. 



truncatus. Swain. 

 *decisus. Lea. Con. 



*clavus. Lam. Con. 

 Unio scalenia. Raf. 

 Unio modioliformis. Say; not of Lea. 



*patulu3. Lea. 



*Ravenelianus.t Lea. 



*Rangianus. Lea. 



*sulcatus. Lea. Eat. Say. 



Unio ridibundus. Say. Eat. (Fe- 

 male.)! 



*Haysianus. Lea. 



*ellipsis.§ Lea. Eat. 

 Unio brevialis 1 Sow. 



*castaneus. Lea. 



CO 



O 

 S 



Ph 



S 

 o 



OVAL. 



*Tampicoensis. Lea. 

 *Lecontianus. Lea. 

 *perdix. Lea. 

 pectorosus. Con. 

 *ventricosus. Bar. 



*occidens.|| Lea. 



Unio ventiicosus. Say. 



*doIabr8Eformis. Lea. 



*globosus. Lea. 



Syni. globosa. Lea, Trans. Am. P. S. 

 Unio capax ? Green. 



*splendidus. Lea. 



*ochraceus. Say. Con. 



Sym. ochracea. Lea. Trans. Am. 

 P. S. 



*cariosus. Say. Bar. 

 Uiiiocariosa.^f Lam. 

 Unio ovata. Valen. 

 Unio luteola. Con.; noi of Lam. 



FAMILIES ! ! See " New Fresh Water Shells of the United States," p. 72, and Mr Rafinesque's " Monographie." 

 In Mr Say's " Synonymy," triangularis, Raf., is considered to be the same as ellipsis (nobis) ! 



t Mr Conrad has subsequently published a different species under this name. 



X For some years I was satisfied that Mr Say's ridibundus was only a variety of siilcalus (nobis). There 

 can now, however, scarcely be a doubt that it is the female of that specie? ; 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 ridibundus in No. 1 of " American Conchology," but does not insert it 

 in his " Synonymy" in No. 6. 



§ Mr Say in his " American Conchology," refigures this, and recognises my name. Subsequently, in his 

 " Synonymy," he makes it a synonym of triangularis, Raf. Mr Conrad says it is olivariits, Raf. 



II 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 suf- 

 ficient light upon them to decide with certainty. Among Mr Barnes's varieties oi venlricosus, it is evident there 

 are several distinct species. 



H U. cariosa, Lam. (Var. 2,) is the Alas, marginata, Say. 



