VARIATION IN NACREOUS COLOR OF NAIADES 221 



Lavender, Deep Vinaceous Gray, Dark 



Vinaceous Gray. 

 Salmon, Straw colored Pale Ochraceous Buff. 



White* Pearl Blue, white. 



Distribution of Colors as a Whole in Upper Ohio Drainage and 

 Lake Erie. (561 shells). 



Pearl Blue with allied colors 18% 



Light Vinaceous Lilac and allied colors 28% 



Light Vinaceous Purple and allied colors 27% 



Deep Vinaceous Gray and allied colors 20% 



Pale Ochraceous Buff and allied colors 05% 



Distribution of Colors as a Whole in Upper Ohio Drainage 

 (509 shells). 



Pearl Blue and allied colors 11% 



Light Vinaceous Lilac and allied colors... 22% 



Light Vinaceous Purple and allied colors 25% 



Purple Drab and allied colors. 12% 



Pale Ochraceous Buff and allied colors 6% 



Distribution of Colors in Upper Ohio Tributaries, etc. 



Alle'ny Alle'ny Mon'g Mon'g Ohio Ohio Beaver Beaver 

 Tribs. River Tribs. River Tribs. River Tribs. River 



Pearl Blue, etc 9%--ii%--i3% - 14% 6%....i4% 6% 



Light Vin. Lilac, etc... 1 7 %--42 %--27 %--33 %--4i %-;-56%--2i %....39% 



Light Vin. Purple, etc...37%-.35 %-'-i4%--6o%....36%....30%.-50%....i i % 



Light Purple Drab. 7 %-- 1 2 %-.46 % 3 % 6 % i o %-.24 % 



Distribution of Colors as a Whole in L. Erie. (52 shells).' 



Light Vinaceous Purple and allied colors.. 27% 



Deep Vinaceous Lavender and allied colors 30% 



Deep Vinaceous Gray and allied colors 23% 



Dark Vinaceous Gray and allied colors..... 18% 



Distribution in Lake Erie — Localities. 



Presque La Plaisance 



Isle Bay 



Light Vinaceous Purple. 20% : 20% 



Deep Vinaceous Lavender 36% 10% 



Deep Vinaceous Gray.... 36 % 50 % 



Dark Vinaceous Gray 10% 20% 



Deductions from Tables of Percentages and PI. III. 



Although pearl blue is represented in L. Erie, the percentage 

 seems small. The colors of the Upper Ohio Drainage seem to be 

 more of a purple lilac, while those of L. Erie are more of a lavender 

 gray. There is at least a distinct lightening of nacreous color in 

 Lake Erie. 



* White was found to occur less than i % in all the shells examined. 



