VSIO. 



49 



o 



Z 



s 



H 

 C 



S 



Z 



c 



f OVAL. 



*fabalis. 1 Zea. Ghenu. Han. 

 Unio capillus. Say, Transylvania 



Journal, vol. v. 

 Unio lapillus. Say, Am. Conch. No. 



5. Con. 



*paulus. Lea. Chenu. 



*corvinus. Lea. 



*Cromwellii. Lea. 



*parvns. Bar. Sh.&Eat. Con. Phili. 

 Kiist. Adams. Han. 

 Mya parva. Eat. 



*corvunculus. Lea. 



*marginis. Lea. 



*germanus. Lea. 



*granulatus. 2 Lea. 



*cylindrellus. Lea. 



*Texasensis. Lea. 



*Bairdianus. Lea. 



& ' 



I 



OVAL. 



*Bealei. Lea. 



*Haleianus. Lea. Chenu. 



*nigerrimus. Lea. 



*minor. Lea. 



*glans. s Lea. Kiist. Chenu. Con. 

 Han. 



involutus. Hanley. Eeeve. 



*nux. Lea. 



*cinnamomicus. Lea. 



*Bnnnbyantis. Lea. 



*concolor. Lea. 



*mcestus. Lea. Chenu. 



*pullus. Con. 



*divaxicatiis. Lea. Yon Mar. Han. 



*Petterianus? Kiist} 

 Unio carneits. Kiist. 



1 Say and Conrad both, in their catalogues, give precedence to lapillus. Fabalis is in my Memoir 

 read before the Am. Philos. Soc, May 7, 1830, and inserted in the Transactions; capillus was first 

 inserted in the December number (1831) of the Transylvania Journal, and subsequently in the Amer. 

 Conch., No. 5 (August, 1832), under the name of lapillus. Mr. Say does not mention why he changed 

 the name on redescription. I should prefer the first, as a more descriptive name, were I to choose 

 between the two. 



2 Probabl}' a marked variety of germanus, Lea. 



3 Mr. Say doubts if the glans be not the same with parvus. I do not see how there can be any 

 difficulty in distinguishing them. The glans is a much heavier shell, and the nacre of all the specimens 

 I have seen is more or less purple, while that of parvus is always, I believe, white. Among many hundred 

 specimens which have come under my notice, I have never seen one of any other color. The texture of 

 the nacre is also totally different, the latter being more pearly than any other of our Uniones. In the 

 epidermis and beaks they also differ essentially. Mr. Conrad describes and figures U. glans, Lea, in 

 Monog., p. 21; but the figure is evidently not glans. It is very like some of the varieties of U. obscurus, 

 Lea. 



4 U. Petterianus and U. carneus were sent to me by Dr. Tandembusch, of Bremen, as distinct species. 

 I believe the latter to be the old of the former, thrown out of its normal form by much erosion at the 

 beaks. They are from Montenegro, and may prove to be only a variety of Unio Batavus. See Kuster's 

 edition of Martini, PI. 26, Fig. 4. 



13 



