﻿I.AMPSIIJS 131 



Lampsii.is ozai^khnsis (Call). 



Shell elliptical, rather solid, not inflated, with a low, rounded 

 posterior ridge, sometimes feebly doubly ridg^ed ; beaks low, 

 their sculpture not seen ; anterior end rounded ; posterior end 

 slightly produced, ending- in a rounded or slightly biangulate 

 point a little below the middle of the height of the shell ; base 

 rounded, a ven- little fuller behind the center ; surface dirty 

 yellowish-green, faintly wavy-rayed or rayless, showing numer- 

 ous, rest periods ; epidermis somewhat cloth-like and dull ; left 

 valve with two stumpy or slightly compressed pseudocardinals, 

 which are nearly equal in size, and two slightly curved laterals ; 

 right valve with one pseudocardinal and a very small tubercle 

 above it. v^ith one lateral, which has a slight ridge along its 

 lower base ; beak cavities shallow, compressed ; muscle scars 

 well marked ; nacre bluish-white, silvery, with a reddish irides- 

 cence behind. Male shell feebly biangulate behind, slightly 

 rhomboid, rounded or scarcely biangulate at the post-basal ter- 

 mination, in front of which there is a slight incurving of the 

 base line. Female shell suhbiangulate behind, the termination 

 alwDUt midway up from the base ; marsupial swelling small, long 

 and rounded, not close to the posterior end. 

 Length 44, height 28, diam. 16 mm. 



Type locality. Current River and its tributaries. Jack's Fork 

 and Big Creek, Shannon County, Mo. Also, White River, Ark. 



Unio ozarkensis Call, Pr. U. S. N. Mus., X, 1887, p. 498, pi. 

 XXVII ; Tr. Ac; Sci., St. Louis, VII, 1895, P- 33, pl- xviii. 



Lampsilis ozarkensis Simpson, Syn., 1900, p. 557. 



This species seems to stand somewhat by itself, though it has 



evident relations with the trabalis and cllipsiformis groups in 



its general form and color pattern. 



Group of Lampsilis trahalis. 



Shell solid, that of the male sinuate at post-base, and some- 

 times produced posteriorly, female shell wider, but slightly 

 sinuous : beak sculpture rather coarse, feebly doubly looped ; 

 epidermis dark, with wavy capillary rays ; hinge heavy ; nacre 

 bluish-white or purple ; animal unknown. 



