544 ORTMANN—NAYADES OF 
it from Edgemoor, Anderson Co., Tenn., and Pilsbry and Roads give 
it from Patton’s Ferry, Roane Co., Tenn.’ I also have found it in 
French Broad River, at Boyd Creek, Sevier Co., Tenn. Records 
from ‘“ Holston River” probably refer to the Tennessee, at any rate, 
it must be a rare shell above Knoxville. 
Type locality: Ohio River. 
21. PLETHOBASUS CyPHyUS (Rafinesque), 1820. 
Obliquaria cyphya Rafinesque, ’20.—Unio @sopus Lewis, ’71.— 
Plethobasus esopus Ortmann, ’12b, p. 260 (anatomy ).—Pleuro- 
bema esopus Simpson, ’14, p. 806.—Pleurobema cyphia Vanatta, 
"15, Pp. 550 7 
In the larger rivers, Tennessee, Clinch, Powell, Holston, and 
French Broad, going up, in the Powell, to Bryant Shoals, Claiborne 
Co; Tenn: ; in the Clinch to Clinchport, Scott: Co., Va.; im the Efol- 
ston to the mouth of the North Fork at Rotherwood, Hawkins Co., 
Tenn. . 
Type locality: Falls of the Ohio. 
22. PLETHOBASUS CYPHYUS COMPERTUS (Frierson), I9ITI. 
Unio varicosus Lewis, ’71.—Unio compertus Frierson, ’11, p. 53, pl. 
3 (middle and lower figures )—Pleurobema compertum Simpson, 
"14, p. 809. 
Specimens in the Walker collection from ‘‘ Holston River, Knox- 
ville,’ are authentically labeled varicosus Lewis, and compertus 
Frierson, and they agree very well with specimens collected by my- 
self in French Broad River, at Boyd Creek, Sevier Co., Tenn. My 
specimens (I have five) are larger than Frierson’s figures, and 
most of them are more drawn out posteriorly. They were found as- 
sociated with one specimen of the true P. cyphyus, and resemble the 
latter very much, except that the radial row of knobs on the disk 
is poorly developed, almost obliterated, and that the soft parts are 
not of orange, but of pale color. (For the rest, the anatomy of male 
and female is like that of P. cyphyus.) 
I consider this as a variety of P. cyphyus, since in some of my 
specimens, the row of knobs is more distinct, and since typical 
