ORTMANN: monograph of the naiades of PENNSYLVANIA. 267 



rays (if rays occur) and no concentric bands indicating growth-rests, by which 

 fact the young of L. luteola may be recognized as being juvenile. Old specimens 

 of L. luteola are much larger. 



There is a great deal of variability in the character of the rays of E. iris, and 

 below I shall discuss a northern race {novi-ehoraci) , the chief difference of which 

 consists in the color-pattern. Otherwise our specimens of E. iris are very imiform 

 in their characters. 



Localities in Pennsylvania represented in the Carnegie Museum: 



Little Beaver Creek, Cannelton ( Miss Vera White) and New Galilee, Beaver Co. ; Enon Valley, LawTence Co. 



Beaver River, Wampum, Lawrence Co. (G. H. Clapp & H. H. Smith)."'' 



SlipperjTock Creek, Wurtemberg, LawTence Co. 



Mahoning River, Mahoningtown and Edinburg, Lawrence Co. 



Shenango River, Harbor Bridge and Pulaski, Lawrence Co.; Jamestown, Mercer Co. 



Neshannock Creek, Eastbrook and Volant, Lawrence Co.; Leesburg, Mercer Co. 



Pymatuning Creek, Pymatuning Township, Mercer Co. 



Buffalo Creek, Harbison, Butler Co. 



Crooked Creek, Rosston, Armstrong Co. 



Sandy Creek, Sandy Lake, Mercer Co. 



French Creek, Cochranton, Crawford Co. 



Leboeuf Creek, Waterford, Erie Co. 



Dunkard Creek, Wiley, Greene Co. 



Cheat River, Cheat Haven, Fayette Co. 



Other localities represented in the Carnegie Museum: 



West Fork River, Lynch Mines, Harrison Co.; Lightburn and Weston, Lewis Co., West Virginia. 



Little Kanawha River, Burnsville, Braxton Co., West Virginia. 



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



Elk River, Shelton, Clay Co.; and Sutton, Braxton Co., West Virginia. 



Little Coal River, Boone Co., West Virginia (Hartman collection). 



James River, Galena, Stone Co., Missouri (A. A. Hinkley). 



Distribution and Ecology in Pennsylvania (See fig. 27) : Like the preceding 

 species {E. fabalis) E. iris is restricted to the Beaver-drainage and certain tribu- 

 taries of the Allegheny and Monongahela, and has been foimd in addition in Little 

 Beaver Creek. It is also present in the upper Monongahela in West Virginia. 

 It has never been found in the large rivers. It seems to prefer localities like those 

 frequented by E. fabalis {Dianthera-patch.es), and is altogether a rare shell. 



General distribution: Type locality, Ohio (Lea). 



The exact range of this species is hard to determine, since it has often been 

 confounded with its var. novi-eboraci, and because there are kindred forms in the 



"^ One specimen determined by Simpson as L. fatuus (Lea). 



