200 



MEMOIRS OF THE CARNEGIE MUSEUM. 



Susquehanna (Cush Cushion Creek); but these came from an old, abandoned 

 reservoir, with a muddy bottom and rich vegetation. 



Specimens from Conneaut Creek, tributary to Lake Erie, do not differ from 

 the normal type. However, in Lake Erie proper a peculiar form is found. I my- 

 self did not find manj' specimens, but I have received additional ones from C. 

 Goodrich, and all these represent a dwarfed race (largest at hand: L. 51 mm.. 



Fig. 21. 



• Strophitus edentulus (eastern half). 

 + Strophitus undulatus. 



H. 28 mm., D. 20 mm.), of a rather regular, subelliptical and elongate outline. 

 I do not, however, think it advisable to distinguish this race by a varietal name. 



Localities in Pennsylvmiia, represented in the Carnegie Mnseum : 



Small tributaries of the Ohio: 

 Buffalo Creek, Acheson, Washington Co. 

 Cross Creek, Avella, Wasliington Co. 

 Little Beaver Creek, Cannelton (H. H. Smith), Darlington, New Galilee, Beaver Co.; Enon Valley, 



Lawrence Co. 

 Raccoon Creek, Raccoon Township and New Sheffield, Beaver Co.; Bavington, Washington Co. 

 Chartiers Creek, Carnegie, Allegheny Co. (D. A. Atkinson & J. L. Graf). 

 Little Chartiers Creek, Morganza, Washington Co. 



Beaver-drainage : 

 Beaver River, Wampum, LawTence Co. (G. H. Clapp & H. H. Smith). 

 Connoquenessing Creek, Ell wood City, Lawrence Co. (G. H. Clapp & H. H. Smith); Celia, Beaver Co.; 



Zelienople, Butler Co.; Harmony, Butler Co. (R. G. Pflaum). 

 Slipperyrock Creek, Wurtemberg and Rose Point, La\vrence Co. 



