52 MEMOIRS OF THE CARNEGIE MUSEUM. 



and the same seems to be true elsewhere, although there are a few exceptions, and 

 it seems that in such cases the main form tends to be replaced by the variety wardi. 



In Ohio the main species hardly occurs outside of the Ohio proper (Sterki, 

 1907a). In Indiana it is known only from the larger rivers, the Ohio, White, 

 Wabash, and Kankakee, and also from Eel, Blue, and Whitewater Rivers (Call, 

 1896 and 1900). In Illinois the same rule seems to prevail, so that its range covers 

 the greater part of the state, except the northern and northeastern extremity 

 (Baker, 1906; Wilson & Clark, 1912a). In the Mississippi-drainage, this species 

 goes uji into the Wisconsin River in Wisconsin, and the Minnesota River in Minne- 

 sota. 



Westward,s it is found as far as southeastern Kansas (Scammon, 1906) and to 

 the southwest it extends to Oklahoma and the Ouachita River in Arkansas (Call, 

 1895; Wheeler, 1918, and our own material). The records from Louisiana and 

 Texas are doubtful. 



South of the Ohio in West Virginia this species is found in the headwaters of 

 the Monongahela (West Fork River), in the Little Kanawha, and in Coal River, 

 but, according to specimens in the Carnegie Museum, in the form wardi. Records 

 from Kentucky and Tennessee are scanty. The type-localit}' is the Kentucky 

 River. It is known from the Cumberland River (Scammon, 1906, and Wilson & 

 Clark, 1914) and our material shows its presence in the Tennessee up to the lower 

 Holston (See also Lewis, 1871). It turns up again in the Alabama system (Lewis, 

 1877, CaU, 1885, Carnegie Museum). Lea's locality (Obs. 10, 1863, p. 430), 

 Columbus, Lowndes Co., Mississippi, belongs with this group of stations. 



This latter set of localities is interesting, in view of Simpson's statement, 

 that it is missing in the lower Mississippi region. If this is correct, it could have 

 reached the Alabama-drainage only by crossing over from the Tennessee-drainage. 

 This case should be kept in mind, for it is of zoogeographical importance. 



QuADRULA CYLiNDRicA (Say) (1817)." 

 Quadrula cylindrica (Say) Simpson, 1914, p. 832. 



Plate V, figs. 1, 2, 3. 

 Records from Pennsylvania: 



Harn, 1891, p. 136 (western Pennsylvania). 



Rhoads, 1899, p. 136 (Ohio River, Coraopolis, Allegheny Co.; Beaver, Beaver Co.; and Beaver River, 



Wampum, Lawrence Co.). 

 Ortmann, 19096, p. 198. 



Characters of the shell: Shell rather large, heavy. Outline elongated sub- 



■" Not 1816 (See footnote 20 under Amblema plicala, p. 25). 



