UPPER TENNESSEE DRAINAGE. 567 
Genus: OxsovariA Rafinesque (1820). 
Ortmann, 12), p. 320. 
51. OBOVARIA (OBOVARIA) RETUSA (Lamarck), 1819. 
Unio retusa Lamarck, ’19—Obovaria retusa Ortmann, 12), p. 321 
(anatomy ).—Obovaria (Obovaria) retusa Simpson, 14, p. 290. 
Reported by Call from the Holston River in east Tennessee, but 
missing in Lewis’s list. There are specimens in the Carnegie Mu- 
seum (from the Smith collection) labeled: Tennessee River, Knox 
Co., Tenn.; and others in the Walker collection labeled: Holston 
River, Knox Co., and Holston River, Knoxville, Tenn. In all these 
cases, apparently, the Tennessee River at and below Knoxville is 
meant. I found this species only once: a young specimen in Clinch 
River, at Clinton, Anderson Co., Tenn. 
In the Walker collection are also specimens from the Tennessee 
at Bridgeport, Jackson Co., Ala., and from Florence, Lauderdale Co., 
Ala. (also reported by Hinkley). 
Thus this species seems to belong to the upper Tennessee fauna, 
going up to Knoxville and into the lower Clinch; but it apparently is 
very rare. 
Some of my specimens of O. subrotunda from the Holston 
(Mascot) have slighly incurved beaks and purple nacre, and resemble 
O. retusa to a dergee. Already Wilson and Clark (’14) have indi- 
cated a similar approaching of the two species in Cumberland River. 
Type locality: ? (Nova Scotia per errorem). 
52. OBOVARIA (OBOVARIA) SUBROTUNDA (Rafinesque), 1820. 
Obliquaria subrotunda Rafinesque, ’20—Unio circulus Lewis, ’71.— 
Unio circulus Pilsbry & Rhoads, ’96—Obovaria circulus Ort- 
mann, ’12b (anatomy ).—Obovaria (Obovaria) circulus Simpson, 
"14, p. 291 —Obovaria subrotunda Vanatta, ’15, p. 552. 
The identity of Obliquaria subrotunda and Obovaria striata 
Rafinesque with U. circulus Lea has been recognized by Conrad in 
1834, who selected swbrotunda as name, which thus must be used. 
Apparently rare in the upper Tennessee region. Reported from 
the Tennessee below Knoxville (Lewis), and at Knoxville (Call, 
