﻿r.AMPSiLis 67 



tured, greenish, waxy-yellow, beautifully and boldly rayed with 

 g-reen. In some case? the rays are broad and very distinct, in 

 others they are split into numerous fine rays with a wider ray 

 of the ground color between them. Occasional shells are scarce- 

 ly rayed at all. Left valve bearing two sharp, sometimes slight- 

 ly compressed pseudocardinals, and often having a small an- 

 terior lamellar third tooth near the edge of the shell ; right 

 valve with two pseudocardinals, the lower the larger ; laterals 

 curved, one in the right valve and two in the left ; anterior 

 muscle scars well marked ; posterior scars faint ; nacre gen- 

 erally rich silvery, though sometimes bluish and lurid brown 

 in the cavity of the beaks. The male shell is somewhat pointed 

 behind about midway up from the base ; that of the female is 

 rather blunt behind and decidedly swollen at the post-base. 



Length (male) 60, height 35, diam. 25 mm. 



Length (female) 57. height 38, diam. 2^ mm. 



Eastern half of Texas; Indian Territory; Arkansas; east to 

 Alabama. 



Type locality, Teche River, la. 

 Unio hydianiis Lea, Tr. Am. Phil. Soc, \7, 1838, p. 14, 



pi. VI, fig. 14: Obs., II, 1838, p. 14, pi. VI, fig. 14.— Han- 



i,EY, Biv. Shells, 1843, P- iQ^, pi. xxiii. fig. 6. — Kuster, 



Conch. Cab. Unio., 1861, p. 201, pi. lxvii. fig. 2. — Chenu, 



111. Conch., 1858, pi. xvii, fig. 3, 7,0. 3^7; pi. XXIV, figs. 7, ya, 



yh. — SowERBV. Conch. Icon., XVI, 1866, pi. xxxvii, fig. 203. 

 Margarita (Unio) hydianus Lea, Syn., 1836. p. 25 ; 1838, p. 19. 

 Margaron (Unio) hydianus Lea, Syn., 1852, p. 28; 1870, p. 44. 

 Lampsilis hydianus Simpson, Svn., igoo, p. 536. 

 Unio placitns Lea, Pr. Am. Phil. Soc. ,V. 1852, p. 252 ; Tr. Am. 



Phil. Soc, 1852, p. 279, pi. xxiii, fig. 38; Obs., ¥.1852, p. 



35, pi. xxni, fig. 38.— KusTER, Conch. Cab. Unio., 1861, p. 



262, pi. LXXXVIII, fig. 2. 

 Margaron (Unio) placitns Lea, Syn., 1852, p. 29 ; 1870, p. 46. 



.A beautiful shell, which is often confounded with L. Inteola. 

 It is smaller than the typical form of that species, the epider- 

 mis has a more waxy texture, it is generally more inflated and 



