UPPER TENNESSEE DRAINAGE. 669 



Genus: Nephronaias Fischer & Crosse (1893).^ 

 Ortmann, '12b, p. 324. 



54. Nephronaias LiGAMENTiNA GiBBA (Simpson), 1900. 



Unio ligamentinus Lewis, '71. — Unio ligamentinus Pilsbry & Rhoads, 

 '96. — Nephronaias ligamentina (incl. gibba) Ortmann, '12b, 

 (anatomy). — Nephronaias ligamentina gibba Goodrich, '13, p. 

 94. — Lampsilis ligamentina gibba Simpson, '14, p. 82. 

 The main species is not represented in the upper Tennessee 

 region, although occasional specimens turn up, which are hard to dis- 

 tinguish from it. The var. gibba is extremely abundant in all the 

 larger rivers: Powell, Clinch, Holston, French Broad, Tennessee, but 

 in the upstream direction it disappears before it reaches the head- 

 waters region. In the Powell, it has been observed up to Shawanee, 

 Claiborne Co., Tenn. ; in the Clinch, up to St. Paul, Wise Co., Va. ; 

 in the North Fork Holston, up to Holston Bridge, Scott Co., Va. ; 

 in the South Fork, up to Pactolus, Sullivan Co., Tenn. From the 

 French Broad it also enters the lower part of the Nolichucky, at 

 Chunn's Shoals, Hamblen Co., Tenn. 



Type locality: " Ohio River and southward." 



55. Nephronaias pectorosa (Conrad), 1834. 



Unio pectorosus Conrad, May, '34. — Unio pcrdix Lea, August, '34. 

 — Unio biangularis Lea, '40. — Unio biangulatns Lea, '43. — U)iio 

 biangulatus Lewis, '71. — Unio biangularis Pilsbry & Rhoads, '96. 

 — Nephronaias perdix Ortmann, '12b, p. 326 (anatomy). — 

 Nephronaias perdix Ortmann, '13&, p. 311. — Nephronaias perdix 

 Goodrich, '13, p. 94. — Lampsilis biangularis and perdix Simpson, 

 '14, pp. 59 and 88. 



The date of publication of U . perdix Lea is incorrectly given by 

 Simpson as 1827. There is no question that biangularis and perdix 

 are the same species, and it is quite astonishing that this identity has 

 not been recognized by Simpson. Recently, Frierson has suggested 

 to me that vittatis Rafinesque, 1831, from Greene River, Ky., might 



1 Possibly the generic name should be changed to Actinonaias; compare 

 Frierson, Nautilus, 31, 1917, p. 48. 



PROC. AMER. PHIL. SOC, VOL. LVII, LL, OCT. I, I918. 



