UPPER TENNESSEE DRAINAGE. 553 
Simpson (p. 804) makes U. striatissimus Anthony a synonym 
of P. estabrookianum (which actually is Fusconaia barnesiana big- 
byensis). Specimens from Blount Co., Tenn., received from the 
Alabama Museum of Nat. Hist. as striatissimus, and similar ones 
with the same label in the Walker collection, agree fully with speci- 
mens collected by myself in Little River in Blount Co., and are 
this form. : 
Walker has four specimens labeled P. swordianum (Wright) 
from the Wright collection, which thus are authentic specimens. 
They are all typical P. owiforme argentewm. In addition, he has 
three others from the Sword collection (original lot), of which two. 
are this form, while the third is Fusconaia pilaris bursa-pastoris. 
The type of swordianum has, according to Simpson, the diameter 
of 40 per cent., and thus would stand under oviforme. This, how- 
ever, seems to be an extreme specimen. 
This is the compressed form of oviforme, peculiar to the head- 
waters and other small streams. It also generally attains a larger 
size than the typical owiforme, and is more rhomboidal in outline. 
Lea’s only type of U. argenteus (examined by myself in Washing- 
ton) is not a normal specimen; it 1s tapering behind, which is a 
character of oviforme. U. planior represents the normal shape of 
this shell, rhomboidal, while U. brevis is exactly the same thing, 
only slightly shorter. The color markings are generally less bright 
than in oviforme, and very often they are obscure or missing, 
chiefly in old shells. 
This variety is found in Powell River from Big Stone Gap, Wise 
Co., Va. (where it alone is present), downward (associated with 
oviforme); in the Clinch, from Tazewell Co., Va., down to Kyle 
Ford, Hancock Co., Tenn. (also associated with oviforme and inter- 
grading with it). In the Holston drainage it is pure in Big Mocassin 
Creek, and in the North Fork at Saltville, Smyth Co., and Holston, 
Washington Co., Va. It is also pure in the Middle Fork at Chil- 
howie, Smyth Co., in the South Fork at Barron, Washington Co., 
Va., and in Watauga River at Watauga, Carter Co., Tenn. Farther 
down, it passes into, and is associated with, oviforme, but has not 
been found in the Holston proper. It is in Little Pigeon River, at 
Sevierville, Sevier Co., Tenn., but not very well developed here, the 
PROC. AMER. PHIL, SOC., VOL. LVII, KK, OCT. 1, 1918. 
