UPPER TENNESSEE DRAINAGE. 555 
Type locality: Holston River, Tenn. (Simpson says: Tuscumbia, 
Ala.) (topotypes examined). ° 
Note: The group of Pleurobema oviforme is also quite abundant 
in the Tennessee drainage in North Alabama. Also here the hol- 
stonense-form is in the Tennessee proper (also in lower part of Paint 
Rock River and Limestone Creek) ; in the tributaries, oviforme is 
the prevailing form, and in some of the headwaters, the argenteum- 
form is fully as well developed as in the upper Clinch and Holston, 
for instance: in Paint Rock River at Princeton, Jackson Co., Ala.; 
Dry Creek, Holly Tree, Jackson Co., Ala. (tributary to Paint Rock) ; 
in Hurricane Creek, Gurley, Madison Co., Ala. (tributary to Flint 
River) ; in Elk River, Estill Springs, Franklin Co., Tenn., and its 
tributary: Boiling River, Cowan, Franklin Co., Tenn. 
It should be remarked that in this region also the true Pleuro- 
bema clava (Lam.) turns up; this species is distinguished by much 
more anteriorly situated, pointed beaks, swollen anterior part of the 
shell, and cuneiformly compressed posterior part. The Carnegie 
Museum has this species from the old Smith collection, labeled Tus- 
cumbia, Ala., and I have seen it also in the Walker coll. from 
Florence, Ala. In addition, in the latter collection, are specimens. 
from Sequatchie River, at Jasper, Marion Co., Tenn. (Wetherby: 
coll.). 
Genus: Extiprio Rafinesque (1820). 
Ortmann, 1912), p. 265. 
33. ELLIpTIO NIGER (Rafinesque), 1820. 
Unio nigra Rafinesque, ’20.—Umnio crassidens Lewis, ’71.—Unio cras- 
sidens Pilsbry & Rhoads, ’96.—Elliptio crassidens Ortmann. 120» 
p. 266 (anatomy ).—Unio crassidens Simpson, ’14, p. 606.—Unio 
crassidens Vanatta, °15, p. 555.—Elliptio nigra, Utterback, ’16 
p. 88. 
The identity of U. migra Raf. is now firmly established (Say, 
Conrad, Kuester, Sowerby, and Vanatta), and it is the species com- 
monly called crassidens. However, the type of crassidens Lamarck, 
1819, is not this, but isthe trapezotdes Lea (Frierson, ’1ga, pe Ze 
Thus Rafinesque’s name should be used for the present species. 
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