VARIATION IN EPIDERMAL COLOR OF NAJADES. 27 1 



Isabella Color — -20% 



Hellebore Green. 20% 



Buffy Olive * 20% 20% 



Distribution of Colors as a Whole in L. Erie (24 shells). 



Brownish Olive. 30'^ I 



Chestnut Brown..... , 3o%^ 



Yellowish Olive.. 20% 



Deep Oh^e.. 10% 



Hellebore Green.....r. 10% 



Distribution in L. Erie, with that in other localities to be 

 compared. 



Presque Mautnee Conneaut 



Isle River Lake 



Brownish Olive ...40% 50%.. 



Chestnut Brown ...20% -50% 



Yellowish Olive 20%... 



Deep Olive 20% 25% 25% 



Hellebore Green 25% 25% 



Deductions from Tables of Percentages etc. 



Shells of L. Erie are olive or yellowish, whereas those of the 

 Upper Ohio are brownish or buffy. 

 In the Upper Ohio 



It is observed that shells become more buffy in color in the 

 lower stretches of French Creek. A color change mostly toward 

 darker green colors is observed going down the Shenango. Shells 

 darken from greenish colors in Padan and Pymatuning Creeks, 

 to brownish colors where they enter the Shenango. Characteristic 

 primary colors are Buffy Citrine in French Creek, Olive colors in 

 the Shenango. As a whole the Allegheny Tribs. stand out for 

 brownish colors; the Beaver for Olive, green, or yellow. 

 In Lake Erie 



Presque Isle possesses colors not found in the Maumee which 

 drains into L. Erie. Conneaut Lake as compared with L. Erie has 

 yellowish rather than brownish epidermal tints. 



Rays of Epidermis 

 Simpson — "often faintly rayed." 34 of the 69 shells showed 

 raying persisting at least until the 8th estimated year. Rays 

 were distinctly medium in testure when compared with those of 

 other species, and were most widely distributed in creeks. The 

 prevailing color was Brownish Olive, and the oldest age recorded 

 was .8 years. 



