﻿LAMPSILIS 53 



higher ; a rounded, narrowed hinge plate ; and one pseudocar- 

 dinal in the rig'lit valve, with a small, narrow one above it, and 

 one rather solid lateral, truncate behind; muscle scars well 

 marked, smooth ; nacre silvery. The female shell has a strong- 

 ly developed marsupial swelling. 



Length 53, height 37, diam. 25 mm. 



Alabama and Black Warrior Rivers. 



Type locality. Alaliama River, Claiborne. Ala. 

 Unio perovalis CoNRAn, New F. W. Shells. 1834, p. 43, pi. n, 



fig. 2; p. 71.— Chenu, Bib. Conch, 1st ser.. Ill, 1845, p. 21, 



pi. I, fig. 2.— KusTER, Conch. Cab. Unio, 1861, p. 257, pi. 



i,xxxvii, fig. 2. 

 Margarita (Unio} pcmraUs'LF.A, Syn.. 1836. p. 24; 1838, p. 19. 

 Margaron (Unio) pcrovaUs Lea, Syn.. 1852, p. 27; 1870, p. 42. 

 Lam psiHs per oralis Simpson, Syn., 1900, p. 531. 



I have seen specimens of What are undoubtedly this from 

 the type locally and they are close to L. darkiana and L. do- 

 liaris. It is a little shorter than the former, and is less sharply 

 pointed behind; it is not quite so much inflated as the latter 

 and the marsupial swelling is possibly a little fuller than in 

 either of these species ; the texture differs a little from that of 

 the other two. However it is quite probable that they all run 

 together, as the combined differences of the three, so far as I 

 have been able to examine material, are less than is seen in L. 

 ventricosa. 

 Lampsius clarkiana (Lea). 



Shell becoming very solid when fully adult, long elliptical, 

 with only moderately full, high beaks, rather inflated, with a 

 strong, dark ligament, which scarcely shows in front of the 

 beaks ; surface smooth except at the ends of the shell, shining, 

 the epidermis being greenish-yellov^/, olivaceous or tawny, 

 sometimes brownish- or blackish and having a peculiar smoky, 

 soft tint as if almost waxy, faintly rayed or rayless ; posterior 

 ridge weM developed and ending rather below the middle of 

 the height of the shell ; left valve with two solid pseudocardi- 

 nals in front of the beak ; these are subcompressed when young, 



