40 MEMOIRS OF THE CARNEGIE MUSEUM. 



the tributaries in Ohio (Tiffin River, Sterki, 1907o, and other places in the Maumee- 

 drainage), and is known from the Kankakee in Indiana (Sterki)/^ from Michigan, 

 lUinois, and Iowa (Sterki, 1907a, Walker, 1894, as schoolcraftensis, and 1898 as 

 pustulosa). That it is found in Iowa, is confirmed by the locality given above, 

 and by Call (1895), while Geiser (1910) reports only puMulosa from the Wap- 

 sipinicon River in northeastern Iowa. The specimens from Missouri and Kansas 

 are fine and typical. Beyond this we do not know much about the distribution 

 of this form, but it is apparent that this variety is more western and northern in 

 its range than the typical pustulosa. 



It should be noted that the form from Lake Erie hardly differs from the normal 

 type of schoolcraftensis, except for the more regular and distinct growth-lines. 

 The route by which it migrated into the lake is indicated by its presence in the 

 Maumee-drain age . 



QuADRULA QUADRULA (Rafincsque) (1820). 



Quadrula lachrymosa (Lea) Simpson, 1914, p. 841; Quadrula quadrula (Rafin- 

 esque) Vanatta, 1915, p. 556; Quadrula quadrula (Rafinesque) Utter- 

 back, 1916, p. 53. 



Plate IV, fig. 1. 

 Records from Pennsylvania: 



Ortmann, 19096, p. 199. 



Characters of the Shell: Shell growing to a rather considerable size, rather 

 heavy. Outline subtrapezoidal or subquadrate, not oblique, not longer, or only 

 slightly longer than high. Beaks moderately prominent, beak-sculpture double- 

 looped, posterior loop slightly tubercular upon the posterior ridge, these tubercles 

 continued upon the ridge as larger or smaller nodules. Anterior loop, toward the 

 disk, breaking up into nodules, and this sculpture is continued upon the disk in 

 an irregular way. Shell moderately swollen or rather flat, with a rather distinct, 

 but narrow, posterior ridge. In front of the latter, there is a broad, shallow furrow, 

 which is generally smooth, without tubercles. There are large nodules upon the 

 posterior ridge, and smaller ones upon the disk in front of the furrow, but the 

 most anterior part of the shell is generally smooth. Nodules and tubercles very 

 varying in number, arrangement, size, and shape; often they are tear-like (verti- 

 cally elongated), but they may be transversely elongated. The nodules of the 

 anterior part of the shell are the direct continuation of the beak-sculpture. Pos- 

 terior slope with more or less distinct nodules, otten arranged in radiating ridges. 



'•■^ Specimens from the Kankakee River are cited as pustulosa by Wilson & Clark (1912«), but they 

 mention the great variability. 



