542 ‘ORTMANN—NAYADES OF 
It is remarkable that I did not find it in the lower parts of these 
rivers, although it has. been reported from the Knoxville region, and 
from the Tennessee in northern Alabama. 
Type locality: Nolichucky River, Tenn. 
17. QUADRULA CYLINDRICA (Say), 1817. 
Unio cylindricus Say,’17—Unio cylindricus Lewis, ’71.—Unio cylin- 
dricus Pilsbry & Rhoads, ’96.—Quadrula cylindrica Ortmann, 
12), p. 256 (anatomy ).—Quadrula cylindrica Simpson, ’14, p. 
832. 
Reported from the Tennessee below Knoxville and from the 
Holston River. It is rather frequent in the larger rivers, and goes, 
in the Holston, up to Hawkins Co., Tenn. In the region of the forks 
it begins to incline toward the next form; however, in Big Mocassin 
Creek, Mocassin Gap, Scott Co., Va., a tributary of the North Fork, 
I found a rather normal cylindrica. In the Clinch, it goes to Clinch- 
port, Scott Co., Va. It is also in the Powell, up to Claiborne Co., 
Denn, 
Type locality: Wabash River. 
18. QUADRULA CYLINDRICA STRIGILLATA (Wright), 1808. 
Unio cylindricus strigillatus Wright, Nautilus, 12, ’98, p. 6—Quad- 
rula cylindrica strigillata Ortmann, ’13), p. 311.—Quadrula cylin- 
drica strigillata Goodrich, *13, p. 93. 
Simpson (’14, p. 834) does not admit this as a separate form; 
but it is a very good and well-marked local race, belonging to the 
headwaters, being compressed, devoid of large tubercles, but thickly 
covered with small ones. 
Its metropolis is in the upper Clinch River. Intergrades between 
this and the main form are found in Scott Co., Va., and thence far- 
ther up, it becomes a pure race, and goes up to Cedar Bluff in Taze- 
well Co., Va. The same conditions prevail in Powell River, where 
it intergrades with the normal type in Claiborne Co., Tenn., and then 
goes up to Pennington Gap in Lee Co. It also exists in North Fork 
Holston, from Hawkins Co., Tenn., to Mendoto, Washington Co., 
Va., and in the South Fork Holston at Pactolus; Sullivan Co., Tenn. 
