UPPER TENNESSEE DRAINAGE. 583 
Distinguished by the distinct and sharp posterior ridge, depressed 
(truncated) posterior slope, and the peculiar, wedge-shaped anterior 
part of the shell. But these characters gradually pass into those of 
the variety ventricosa. 
The typical L. ovata is restricted to the larger rivers, and quite 
abundant there. It is in the Tennessee, the Little Tennessee, Hol- 
ston, Clinch, and Powell. In the Powell, it goes up to Shawanee, 
Claiborne Co., Tenn. ; in the Clinch, to Clinchport, Scott Co., Va. It 
is the prevailing form in the Holston proper, but does not go into the 
Forks of the Holston. All along its range, and chiefly above Knox- 
ville, it is accompanied by the var. ventricosa, and intergrades with 
it. But at the points just named, it disappears, and leaves the field 
to ventricosa. 
Type locality: Ohio River. 
72, LAMPSILIS OVATA VENTRICOSA (Barnes), 1823. 
Unio ventricosa Barnes, ’23.—Lampsilis ventricosa Ortmann, ’12), 
p. 351 (anatomy ).—Lampsilis ovata ventricosa Ortmann, ’130, Pp. 
311.—Lampsilis ovata ventricosa Goodrich, ’13, p. 95 —Lampsilis 
ventricosa Simpson, ’14, p. 38. 
According to Vanatta (715, p. 551), the type of Lampsilis car- 
dium Rafinesque, ’20, is this, and also Conrad (’34) says so. How- 
ever, this conflicts with Rafinesque’s description, from which it is 
evident that L. cardium is the female of L. ovata. We have here a 
case where the “type” does not agree with the original description, 
and it should be borne in mind that the co-called “types” of Rafin- 
esque, in the Philadelphia Academy, are not types in the strict sense, 
but merely “ authentic specimens ” of somewhat doubtful value. 
In this variety, the posterior ridge becomes indistinct, the pos- 
terior slope is not excavated, and the anterior part of the shell is not 
remarkably compressed. Also, the shell is generally less convex. 
But there are all stages of transition. The upper Tennessee form of 
ventricosa very rarely has the distinct rays of the corresponding 
form of the upper Ohio region. 
L. ovata ventricosa is found associated with the normal L. ovata 
in the larger rivers, but is less frequent there. It goes, however, 
