50 



UKIO. 



OVAL. 



D'Orh. Han. 



*ineptus. Lea, 



■*Wynegungaensis. Lea. Blan. 



*Burroug'hianus. Lea. D^Orh. Hiqje. 

 Von Mart. Han. 



*vestitus. Lea. 



*Wlieatleyaniis. Lea. 



*riidus. Lea. 



*Tecomatensis. Lea. 



*cliscus.^ Lea. Chenu. Han. 

 Unio Panacoe7isis. V. d. Buscli. 



Phili. 

 Unio Mexicanus. Sow. Reeve. 



*siniiis. Lea. Chenu. Han. 



*plancus. Lea. 



multidentatus. Phili. 



*]Sriloticus. Caill. Fer. Desh. Han. 

 Menlce. Potier. Chenu. 

 Mya pictorum. Forkael. 

 Unio pumilis. Zieg. 

 Unio Pareyssi. Phili. 



'OVAL. 



corlDis. Benson? Blan. 



*Egyptiacus. Caill. Fer. Desh. Po- 

 tier. H. Adams. Han. 

 Unio eucyphus. Boury. 



Gviadecliaudii. Eyd. Blan. 



*Bonneaudii.^ Eyd. Blan. 



OBLONG. 



*brevidens. Lea. Chenu. Han. 

 Unio interruptus. Con. 



*tetralasnius.'' Say. Desh. Con. Han. 



*trifidus. Lea. 



■*camptodon.' Say. Han. 

 Unio declivis.^ Con. 

 Unio Sayii. Tapipian. Con. 

 Unio electrinus. Peeve. 

 Unio rhomboideus. Dr. Ward's MSS. 

 U7iio subcroceus. Con. 



■^Columbensis. Lea. 



Jamesianus. Lea. 



"obesus. Lea. Han. 

 Unio rivularis. Con. 



*Bissellianus. Lea. 



^ Unio discus is found in Moctizuma River, Central America, and occurs white, and beautifully 

 salmon color, as well as purple. 



^ Very like U. Niloticus, Fer., and may be only a variety. 



" I am verjr much inclined to think Bonneaudii will prove to be the same with Niloticus. 



* Tetralasmus will, I think, prove to be a large and perfect camptodon.i Saj'. 



'■ This fine shell, as well as tetralasmus, both of which are Mr. Say's, seem to have been over- 

 looked in the formation of his catalogue. They are described in his Amer. Conchology. I have never 

 seen the shell he calls tetralasmus — they may possibly prove to be the same. 



^ The shell in the Academy of Nat. Sci., described and figured by Mr. Conrad, in his Monography, 

 J). 45, as decUvis, Say, I consider to be a middle-aged camptodon, SaJ^ This, however, is not the opinion 

 of all our conchologists. Professor Kirtland, in his Ohio Eeport, saj's that a shell answering Say's 

 description of declivis is found in some of the tributaries of the Scioto River. This is the shell since 

 described \>j Judge Tappon as U. Sayii, but which I have alwaj^s believed to be camptodon. 



