﻿LAMPSTUS III 



i^AMPSILlS CONSTRICTA (Cotirad). 



Shell rather small and short, subelliptical, subsolid, subcom- 

 pressed ; beaks not elevated, their sculpture evenly doubly- 

 looped ridges ; surface nearly smooth or marked with irregular 

 concentric growth lines : rather shining, yellowish-green, or 

 bottle-green, feebly rayed ; hinge somewhat solid ; there are 

 two pseudocardinals in the left valve and one and a faint sec- 

 ond in the right ; one straight lateral in the right valve and two 

 in the left ; anterior muscle scars separate, somewhat impressed ; 

 posterior scars faint; nacre bluish, sometimes purplish in the 

 center, slightly thicker in front. The female shell is pointed 

 behind a little more than midway up from the base, and be- 

 tween this point and the small marsupial swelling tJie outline 

 is generally a little emarginate. The male shell is often sub- 

 rhomboid, the posterior point being generally less than midway 

 up from the base. 



Length 38, height 26, diam. 15 mm. 



James River, Virginia ; south to South Carolina ; Floyd Coun- 

 ty, northwest Georgia ; northern Alabama ; Tennessee. 



Type locality. North River, Rockbridge Co., Va. 

 Unio lienosits var. constnctiis Conrad, Monog., X, 1838, p. 91,. 



pi. XLix, fig. 4. 

 Unio constrictus Conrad, Pr. Ac. N. Sci. Phila., YI, 1853, p. 



247. — SowERpy, Conch. Icon., XVI, 1868, pi. lxxxvii, fig. 



464. 

 Maroaron (Unio) constrictus Lea. Svn., 1852, p. 29: 1870, p. 



Lampsilis constrictus Simpson, Syn., 1900, p. 551. 

 Unio genthii Lea. Pr. Ac. N. Sci. Phila., I, 1857, p. 85 ; Jl. Ac. 

 N. Sci. Phila., 1862, p. 57. pi. ti. fig. 204; Obs., VITI. 1862, 



p. 61, pi. IT, fig. 204. 



Margaron (Unio) genthii Lea, Syn.. 1870, p. 41. 



There is quite a little difference in the degree of inflation 

 and form of this shell ; some specimens are subinflated and 

 others are slightly elongated. It is distinguished from nearly 

 allied forms by the shape of the post-basal swelling which as 

 a rule does not project below the base line of the shell, and 



