uxio. 



I 

 t> 



c 



Y. 



OBLONG. 



*fulvus. iea. Han. 

 Unio icterinus. Con. 



*rufusculus. Lea. 

 *Gibbesianus. Lea. 

 *sordidus. Lea. 

 *Dariensis. Lea. Chenu. 

 *Congarseus. Lea. Chenu. Han. 

 *merus. Lea. 

 *Charruanus. 1 D'Orl. 

 rlmacoicus. D'Orl. Von Mar. 

 *neglectus. Lea. 

 *subplanus. Con. 

 *manubius. Gould? 



*declivis. Say. Desk. Kilst. Han. 

 Unio geometricus? Lea. 

 Unio excultus. Con. 



*paludicolus. Gould. 



*Blandingianus. Lea. Kust. 

 Unio rivicolus. Con. 



*quadratus. Lea. 



OBLONG. 



*depressus. Lam. Less. Chenu. Kust. 



Han. 



Unio Balonnensis.* Con. 

 Unio amliguus. Phil. 

 Unio profuyus. Gould. 

 Unio Amjasi. Reeve. (No. 282.)* 



angustus. Lam. Han. 

 *cacao. Lea. 

 *modestus. Fer. 

 *suavidicus. Lea. 



famelicus. Gould. 

 *Coucliianus. Lea. 



*litoralis. Drop. Lam. Mill. Pfeif. 



Rossm. 6 Des Moul. Grat. Brard. 



Desk. Cuv. Maton and Racket. 



Bouil. Gras. Bronn. More. Mer- 



met. Gassies. Goupil. Diqniy. 



Puton. Potier. Graells. Mouss. 



Han. Caill. 

 Unio crassus. Nil. Phili. Menke. 



Rossm. Moq. 

 Unio Irevialis. Lam. 

 Unio nana. Lam. Dup. Bourg. 

 Unio subtetragona. Mich. Dup. 



Merm. Graells. Gras. 

 Unio incurvus. Lea. Chenu. 

 Unio Pianensis. Farines. Dup. 



Graells. 

 Unio granosus. Schum. 



I The two specimens sent to me by M. D'Orbigny are much smaller than the adult figured by him 

 in Voy. Am. Her., and although very like delodontus, Lam., are different in outline and in some minor 

 characters. 



I 1 am disposed to believe that this is only a variety of declivis, Say. I have specimens from Texas 

 which indicate this. 



3 1 do not find this or declivis in Mr. Say's Synonymy. He has, however, priority. 



4 In a subsequent paper, Jl. A. N. S., vol. ii. p. 295, Mr. Conrad says that, in referring the shell to 

 (Jepressus, Lam., I have committed "an oversight." I do not admit this, but consider myself to be cor- 

 rect, having long had a specimen of U. depressus in my possession, and having seen it frequently in 

 various cabinets in Europe. 



6 Mr. Reeve cites my MS. for this name. I have no recollection of it. 



6 Rossmassler, Iconographie, vol. iii. p. 36, describes a variety under the name of umbonatus. 



