OKTMANN: monograph op the naiades of PENNSYLVANIA. 223 



Distribution and Ecology (See fig. 23) : Type locality, unknown. The original 

 type locality (Nova Scotia) is erroneous. 



Only two specimens have ever been found in Pennsylvania, both at the same 

 place in Beaver Co. This marks the farthest point upstream in the Ohio of the 

 range of this species. 



Simpson (1900) gives the range as "Ohio, Cumberland, and Tennessee River 

 systems." To these it seems to be restricted, and in the middle and upper Ohio, 

 it is also restricted to this river, and does not go into the tributaries (For Ohio see 

 Sterki, 1907a). In Indiana and Illmois, however, it has spread into the larger 

 affluents. Call (1896a, and 1900) reports it for Indiana from the Wabash, White, 

 Whitewater, Patoka, Eel, and Kankakee,"^" and Baker (1906) gives it for Illinois 

 from the Wabash and Spoon Rivers, as far north as La SaUe Coimty. It is also 

 found in the lower Ohio (in Indiana and Illinois), and in the Mississippi River, 

 according to Call (1895, p. 47) "north of Arkansas," but it is missing in Witter's 

 list (1878) of the shells from Muscatine, Iowa, and in Pratt's list (1876) from 

 Davenport, Iowa. 



0. retusa is known from the Cumberland River (Wilson & Clark, 1914; also 

 previously reported from Nashville, Davidson Co., Tennessee, by Call, 1895). 

 In the Tennessee it goes up to the region of Knoxville, entering here the lower 

 Clinch. 



It is unknown from west of the Mississippi and from the Gulf -drainage, and 

 thus the species is rather restricted in its distribution, and is apparently a form of 

 the larger rivers. In the Ohio between Pittsburgh and Cincinnati I found it asso- 

 ciated with the bank-forming shells, and it is here regularly taken by the clam- 

 diggers, but rejected on account of the color of the nacre. In a few cases, I col- 

 lected it in smaller branches of the Ohio in fine gravel, most abundanth' at Portland, 

 Ohio. 



Obovaria (Obovaria) subrotunda (Rafinesque) (1820). 



Obovaria circulus (Lea) Simpson, 1914, p. 291; Obovaria subrotunda (Rafinesque) 

 Vanatta, 1915, p. 552. 



Plate XIV, figs. 1, 2. 

 Records from Pennsylvania: 



Lea, Obs. I, 1834 (Monongahela River, Pittsburgh). 



Ham, 1891 (western Pennsylvania). 



Rhoads, 1899 (Oiiio River, Coraopolis, Alleghenj' Co.) (reported as U. lens). 



Ortmann, 19096, p. 192. 



'"" Also from the Maumee-drainage (St. Joseph River) but this surely needs confirmation. It is 

 also said to be present in a few small lakes in northern Indiana. 



