266 THE AMERICAN MIDLAND NATURALIST 



where an Olive hue is taken on, and to some extent is evident in 

 the Shenango and the Mahoning Rivers. Characteristic primary 

 colors are Yellowish Olive for the Shenango, and Varley, (bright) 

 Green for the Mahoning. .Shells from the Ohio are deeper in color 

 than those from Raccoon Creek, a comparatively near tributary. 

 The Allegheny Tribs. have the most Brownish Olive, the Monon- 

 gahela Tribs. the most dark brown, greenish colors are most abun- 

 dant in the Beaver Tribs. 



In Lake Erie 



Yellow colors predominate at La Plaisance Bay, Olive at Cedar 

 Point and these are equivalent at Presque Isle. 



Rays of Epidermis 



Simpson^ — "rarely faintly rayed, but showing 3 broad dark rays 

 on the posterior slope." Only a few specimens from creeks were 

 noted. In these the rays were bright green and medium in texture. 

 They were present at least until the 14th year. 



Relation of Epidermal Color to Estimated Age of Animal. 



In the Upper Ohio Drainage, Brownish rather than Yellowish 

 Brown increases with age, but at old age, these colors seem to be 

 equally prevalent. The old age colors of brown appear at 6-8 years 

 in both groups of shells and may be complete at this age. L. 

 Erie shells are mostly green at first. No colors seemed peculiar 

 to any given age. 



Observation on Sex-Correlative Coloration as associated with Epider- 

 . mal Color. (8 shells) 

 In this small number of shells, 'males were distinguished by a 

 preponderance of Olive colors; females ranged from yellowish 

 green to brownish hues. 



7. — Paraptera fragilis 



SIMPSON RIDGEWAY 



Greenish yellow Olive Lake, Deep Colonial Buff, Yellowish 



Citrine. 

 Pale Smoky brown Brownish Olive, Buffy Olive. 



Dark Colored Ecru Olive. 



Distribution of Colors as a Whole in Upper Ohio Drainage and 

 L. Erie (58 shells). 



Ecru Olive 30% 



Deep Colonial Buff 20% 



