﻿OBIJOUARIA 



329 



muscle scars very small, smooth, impressed ; nacre white, much 

 thicker in front. 



Length 76, height 67, diam. 40 mm. 



Kansas; Missouri; Indian Territory; Arkansas. 



Type locality, Verdigris River, Ark. 

 Unio aberti Conrad, Pr. Ac. N. Sci. Phila., V, 1850, p. 10; Jl. 



Ac. N. Sci. Phila., 1854, p. 295, pi. xxvi, fig. i. 

 Margaron (Unio) aberti Lea, Syn., 1870, p. 34. 

 Cyprogema aberti Simpson, Syn., 1900, p. 610. 

 Unio popenoi Cali,, Bull. Washb. Coll., L 1885, p. 49, pi. n. 



Larger, less inflated and having a wider hinge plate than 

 C. irrorata. 



Var. lamarckiana Lea. 



Smaller, more truncate behind, darker than the type, and 

 apparently well worthy of a varietal name. 



Arkansas. 



Type locality, Caddo River and CJuachita River, Hot 

 Springs, Ark. 

 Unio lamarckianus Lea, Tr. Am. Phil. Soc, X, 1852, p. 266, 



pi. XVII, fig. 20; Obs., V, 1852, p. 22, pi. XVII, fig. 20. — Sow- 



ERBY, Conch. Icon., XVI, 1868, pi. xcii, fig. 498. 

 Margaron (Unio) lamarckianus Lea, Syn., 1852, p. 23. 



Genus OBLIQUARIA (Rafinesque 1820) Simpson. 



Obliquaria Rafinesoue, Ann. Gen. Sci. Phys. Brux., 1820, p. 



301. — Simpson, Syn., 1900, p. 610. — -Ortmann, Ann. Car. 



Mus., VIII, 1912, p. 309. 



Shell inflated, solid, oval, ending in a tolerably sharp point 

 behind, having a row of large, compressed, longitudinal knobs 

 running from the beaks to the center of the base, those of one 

 valve alternating in position with the knobs of the other, and 

 a well-developed posterior ridge, the space between the ridge 

 and knobs somewhat excavated ; posterior slope and sometimes 

 the entire shell more or less corrugately sculptured ; beaks 

 prominent, incurved, and pointed slig-htly forward toward a 



