ORTMANN: monograph of the naiades of PENNSYLVANIA. 119 



Shenango River, Harbor Bridge and Pulaski, Lawrence Co.; Siiarpsville, Clarksville, Shenango, and 



Jamestown, Mercer Co.; Linesville, Crawford Co. 

 Pj'matiining Creek, Pymatuning Township, Mercer Co. 

 Little Shenango River, Greenville, Mercer Co. 

 Randolph Run, Hartstown, Crawford Co. 



Allegheny-drainage : 

 Cowanshannock Creek, Rural Valley, Armstrong Co. (N. M. Grier). 

 Sandy Creek, Sandylake, Mercer Co. 



French Creek, Utica, Venango Co.; Cochrantoii, Crawford Co.; Union City, Erie Co. 

 Conneaut Outlet, Conneautlake, Crawford Co. 

 Cussewago Creek, Mosiertown, Crawford Co. (H. & L. Ellsworth). 

 Conneauttee Creek, Edinboro, Erie Co. 

 Brokenstraw Creek, Garland, Warren Co. 

 Connewango Creek, Russell, Warren Co. 

 Potato Creek, Smethport, McKean Co. (P. E. Nordgren). 



Lake-drainage: 

 Conneaut Creek, West Springfield, Erie Co. 

 Lake Erie, beach-pools of Presque Isle, Erie, Erie Co. 

 Genesee River, Genesee, Potter Co. 

 Cryder Creek, Genesee, Potter Co. 



Other localities represented in the Carnegie Museum: 



Lake Erie, Cedar Point, Erie Co., Oliio (C. Brookover). 

 Tenmile Creek, Lucas Co., Ohio (C. Goodrich) (lake-drainage). 

 Beaver Creek, Williams Co., Ohio (C. Goodrich). 

 Raisin River, Adrian, Lenawee Co., Micliigan (C. Goodrich). 

 West Branch Nimishillen Creek, Canton, Stark Co., Ohio. 

 Tuscarawas River, Tuscarawas Co., Ohio (Holland collection). 

 North Fork Hughes River, Cornwallis, Ritchie Co., West Virginia. 



Distribution and Ecology in Pennsylvania (See fig. 12): The distribution of 

 this species in Pennsylvania is very peculiar, but, as we shall see later, there are 

 several similar cases. It belongs exclusively to the northwestern part of the state, 

 including Little Beaver Creek, the drainage of Beaver River and most of its tribu- 

 taries, some tributaries of the middle and upper Allegheny (Cowanshannock, Sandy, 

 French, Brokenstraw, Connewango, Potato Creeks), Lake Erie and its drainage, 

 and the upper Genesee River. It has never been found in the Allegheny proper 

 and its drainage from Armstrong Co. down, and is entirely missing in the Ohio 

 l^roper and in the whole Monongahela system. 



Thus it seems as if this species in its distribution does not follow the courses 

 of the rivers, but rather goes across country in the northwestern part of the state, 

 and the relation of its area to that of the Glacial deposits is very close. Only in 

 Little Beaver Creek, below New Galilee, in Brush Creek (tributary to the Con- 



