UPPER TENNESSEE DRAINAGE. 585 



74. Lampsilis orbiculata (Hildreth), 1828. 



Unio orbicnlatus Hildreth, '28. — Lampsilis orbiculata Ortmann, 'i2h, 

 p. 343 (anatomy). — Lampsilis orbiculata Simpson, '14, p. 76. 



Not reported previously from the upper Tennessee region, but 

 in the Walker collection are two specimens labeled "Holston R., 

 Tenn.," which come from the Lewis collection (and thus probably 

 are from the Tennessee). I have found myself two specimens in the 

 Clinch, one at Offutt, Anderson Co., the other at Solway, Knox Co., 

 Tenn. 



This species is also in the Tennessee in North Alabama, at the 

 mussel shoals near Florence (reported by Hinkley, and represented 

 in Walker coll. and Carnegie Mus.). 



Type locality: Muskingum River, Marietta, Ohio. 



Genus: Truncilla Rafinesque (1820). 



Ortmann, '12b, p. 354. 



The subgenera distinguished by Simpson require revision, also 

 with regard to nomenclature. I disregard them for the present, re- 

 marking only that the soft parts furnish good criteria for their defi- 

 nition. 



75. Truncilla Triquetra Rafinesque, 1820. 



Truncilla triqueter Rafinesque, '20. — Unio triangularis Lewis, '71. — 

 Unio triangularis Pilsbry & Rhoads, '96. — Truncilla triquetra 

 Ortmann, '12b, p. 355 (anatomy). — Truncilla triquetra Simpson, 

 '14, P- 5- 



Rather frequent both in larger and smaller rivers, but nowhere 

 in great numbers. Tennessee below Knoxville (Lewis) and at 

 Knoxville (Pilsbry & Rhoads) ;, Little River in Knox Co. (Walker 

 coll.) ; lower Nolichucky; Holston River up to the South Fork at 

 Paotolus, Sullivan Co., Tenn., and the North Fork at Mendota, 

 Washington Co., Va. ; in the Clinch up to Chnchport, Scott Co., Va. ; 

 in the Powell, up to Shawanee, Claiborne Co., Tenn. 

 Type locality: Falls of the Ohio. 



PROC. AMER. PHIL. SOC, VOL. LVH, MM, OCT. I, I918. 



