50 



UNIO. 



H 

 Y- 

 O 



t— ( 



V. 



P 



Eh 

 O 



w 

 s 



CO 



S3 



O 



OVAL. 



*faba. 



Z>'(M. San. 



*ineptus. Zees. 



*"Wynegungaensis. Ze«. Blan. 



*Burroughiamis. Lea. J) 1 Orb. BTupi. 

 Von Hart. Han. 



*vestitus. Lea. 



*Wheatleyanus. Lea. 



*rudus. Lea. 



*Tecomatensis. Lea. 



*diseus. 1 Lea. Chenu. Han. 

 Unio Panacoensis. V. d. Busch. 



Phili. 

 Unto Mexicanus. Sow. Reeve. 



*simus. Lea. Chenu. Han. 



*plancus. Lea. 



nraltidentatus. Phili. 



*Niloticus. Caill. Fer. Desk. Han. 

 Menlce. Potier. Chenu. 

 Mya pictorum. Forhael. 

 Unto pumilis. Zieij. 

 Unio Pareyssi. Phili. 



OVAL, 

 corbis. 



Benson? Blan. 



*Egyptiacus. Caill. Fer. Desk. Po- 

 tter. H. Adams. Han. 

 Unio eucyphus. Bounj. 



Guadecliaudii. Eyd. Blan. 



*Bonneaudii. 3 Eyd. Blan. 



OBLONG. 



*brevidens. Lea. Chenu. Han. 

 Unio interruptus. Con. 



*tetralasmus. 4 Say. Desh. Con. Han. 



*trifidus. Lea. 



*camptodon. 5 Say. Han. 

 Unio declivis. 6 Con. 

 Unio Sayii. Tappan. Con. 

 Unio electrinus. Peeve. 

 Unio rhomboideus. Dr. "Ward's MSS. 

 Unio subcroceus. Con. 



*Columbensis. Lea. 



Jamesianus. Lea. 



*obesus. Lea. Hart. 

 Unto rivularis. Con. 



*Bissellianus. Lea. 



1 Unto discus is found in Moctizuma River, Central America, and occurs white, and beautifully 

 salmon color, as well as purple. 



2 Yery like U. Niloticus, Fer., and may be only a variety. 



3 I am very 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, Say. 



5 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. 



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

 p. 45, as declivis, Say, I consider to be a middle-aged camptodon, Say. This, however, is not the opinion 

 of all our conchologists. Professor Kirtland, in his Ohio Report, sa} T 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 by Judge Tappon as U. Sayii, but which I have always believed to be camptodon. 



