﻿138 I.AMI'SII.IS 



Unio preiostianus Sowkkisy, Conch. Icon., XVI, 1868, p!. 



i.xiii, fig. 315. 

 Unio subangiilatus Sovvhkby, Conch. Icon., XVI, 1868, pi. lxv, 



fig- 3^7- 

 Var. nigrina (Lea). 



Shell generally smaller than the typical form, more narrowed 

 in front, thinner, darker colored and less shining. The nacre 

 is coppery or purplish. 



Length 55, height 33, diam. 18 mm. 



Florida, south to the Hillsborough River. 



Type locality, West Florida. 

 Unio nigrinus Lea, Tr. Am. Rhil. Soc, X, 1852, p. 284, pi. 



XXIV, fig. 44; Obs., V, 1852, p. 40, pi. XXIV, fig. 44. 

 Margaron (Unio) nigrinits Lea, Syn., 1852, p, 39; 1870, p. 62. 

 Lampsilis 7nbex var. nigrinus Simpsox, Syn., 1900, p. 560. 

 Unio ftoridensis S. H. Wright, Conch. Exchange, II, 1888, p. 



105. 

 Unio az\mllii \\. II. Wright, Pr. Ac. N. Sci. Phila., XXIII, 



1888. p. 115, pi. Ill, fig. 2. 



An abundant, rather widely distributed form and quite vari- 

 able. Lea's suhellipsis is generally a little solider and more 

 narrowly rayed than the average forms, but it hardly seems to 

 me to be worthy of a varietal name. I have seen shells from the 

 Cahawba River, Alabama, which are, no doubt, genuine vihex. 

 though they are more inflated and pointed behind than speci- 

 mens found elsewhere, but I do not think they are specifically 

 or even varietally different from exiguus, rutilans or suhellip- 

 sis. 



Lampsilis dispar (Lea). 



Shell long elliptical, scarcely subinflated, subsolid, with a 

 low, rounded posterior ridge ; beaks rather low, their sculpture 

 not seen ; surface with fine growth striae, often showing faint, 

 radiating rows of short wrinkles ; tawny, pale yellowish or 

 yellowish-green with rather feeble ravs on the front part of the 

 shell, but more developed on the hinder part, where they are 



