VARIATION IN EPIDERMAL COLOR IN NAJADES. 267 



Brownish Olive 20% 



Olive Lake... 20% 



Buffy Olive 10% 



Distribution of Colors as a Whole in Upper Ohio Drainage 

 (28 shells). 



Ecru Olive 20% 



Olive Lake 20% 



Brownish Olive ^. 20% 



Buffy Olive.. 20% 



Yellowish Citrine 20% 



Distribution of Colors as a Whole in Upper Ohio Tributaries, 

 and River. 



Alleghenv Ohio 



River River 



Ecru Olive -20% 



Olive Lake. , 25% 20% 



Brownish Olive ...."'....*..... 5o%- 40% 



Buffy Olive ., 25%.. 



Yellowish Citrine... 20% 



Distribution of Colors as a Whole in L. Erie (30 shells). 



Deep Colonial Buff / .'. 30% 



Brownish Olive.. ...20% 



Saccardos Olive. i.....'. 20% 



Ecru Olive 20% 



Grayish Olive ^ 10% 



Distribution of Colors in L. Erie — Localities. • 



La Plaisance Cedar PresQtie Isle 



Bay Point Bay 



Deep Colonial Buff .-25 9o, ....50% 20% 



Brownish Olive 25% --20% 



Saccardos Olive : , 25% 



Ecru Olive -.25%.- --25% - 40% 



Grayish Olive 25%... 20% 



Deductions from Tables of Percentages and PL III. 



Shells from L. Erie arc lighter than those from L- Erie although 

 both possess many colors in common. Buff colors predominate in 

 the former. 

 In the Upper Ohio Drainage 



Shells darken, both primarily and secondarily in going down 

 stream from the Allegheny to the Ohio. Olive Lake is a character- 

 istic primary color for the former, Buffy Citrine for the latter. 

 In Lake Erie 



Buff colors are in the lead at Cedar Point, Olive at Presque 

 Isle, while Grayish Olive seems wanting at La Plaisance Bay. 



