28 



SYNOPSIS OF 



creperus. Lea. 

 glaber. Lea. 



Hildrethianus.* Lea. 

 Al. ambigua? Say. 



fabalis.t Lea. 



Unio capillus. Say, Transylvania Journal, 



Vol. V. 

 U. lapillus. Say, Am. Conch., No. 5. Con. 



parvus. Bar. Eat. 

 Unio parvus. Con. 



glans.:]: Lea. 



* I retain this species among the Uniones, although it does not possess a 

 perfect lateral tooth. As it is, however, thickened along the dorsal margin, 

 and puts on the appearance of a tooth, I have concluded that it was better not 

 to remove it to the S. G. JMargaritana, to which it has little resemblance in 

 its general characters. These observations may apply to U. oriens (nobis), 

 and partially to U. monodontu, Say, ( U. soleniformis, nobis.) Mr. Say's 

 description of ambigua answers well to Hildrethiumis, but I am not sure it is 

 the same, as he has given no figure of it. He seems to have abandoned it, as 

 he does not insert it in his " Synonymy." Mr. Conrad also avoids the inser- 

 tion of it in his Synoptical Table. 



j Say and Conrad both in their catalogues give precedence to lapillus. Fa- 

 balis is in my Memoir read before the Am. Philos. Soc, May 7, 1830, and in- 

 serted in the Transactions; capillus was first inserted in the December num- 

 ber (1831) of the Transylvania Journal, and subsequently in the " Amer. 

 Conch." No. 5, (Aug. 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, if I were to choose between the two. 



i, 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 



