554 . ORTMANN— NAYADES OF 



majority of the specimens belonging to oviforme. In Little River, 

 at Walland and Melrose, Blount Co., Tenn., it is well developed, 

 pure, and not accompanied by oviforme. The Little River form has 

 been called striatissunius, and it has one peculiarity in the soft 

 parts ; they are of the orange type, and the placentae are red. P. ovi- 

 forme argenteiim is also in the tributaries of Hiwassee River (in 

 Conasauga Creek with oviforme), and in South Chickamauga Creek, 

 at Ringgold, Catoosa Co., Ga. The latter specimens have, in the 

 average, a greater diameter, resembling that of oviforme, but they 

 are stunted in growth (truncated behind). A few of normal shape 

 are clearly argenteum. In the larger rivers, this form is missing. 



Type locality: Holston River, Tenn. (not recently found in Hol- 

 ston proper), 



32. Pleurobema oviforme holstonense (Lea), 1840. 



Unio holstonensis Lea, '40. — Unio mimdus Lea, '57. — Unio tes- 

 serulce Lea, '61. — Unio patfinoides Lea, '71. — Unio acucns Lea, 

 '71. — Unio /azt'JLea, '71. — Unio holstonensis a.r\d fesserulce Lewis, 

 '71. — Unio beUulns Lea, '72. — Unio acucns and laivi Pilsbry & 

 Rhoads, '96. — Plnerobema holstonense, acucns, and tcsscrulce 

 Simpson, '14, pp. 739, 746, 749. 



U. miindns, lazvi, patfinoides, and hclhdiis have already been rec- 

 ognized by Simpson as synonyms of P. holstonense. 



This is the swollen, large river form, of oviforme. U. holstonensis, 

 pattinoides, acncns, and lazui are less swollen than the others {miin- 

 dns, tessernlce, bcllulns), but they all pass gradually into each other 

 with regard to obesity. 



This form has been reported from the Tennessee below Knox- 

 ville, and down to the mussel shoals in ^northern Alabama ; and fur- 

 ther from the lower Clinch, the lower Emory River, and the Noli- 

 chucky. According to the material examined by the writer, it goes 

 up, in the Clinch, to Edgemoor, Anderson Co., Tenn. ; in the Hol- 

 ston, to Mascot, Knox Co., Tenn. ; it is in French Broad at Boyd 

 Creek, Sevier Co., Tenn. ; in Little Tennessee River, ]\Ionroe Co., 

 Tenn. (Walker coll.); and. in the Hiwassee at Austral, Polk Co., 

 Tenn. At all these points, near its upper limit, it is associated and 

 intergrades with oviforme. 



