VARIATION IN NACREOUS COLOR OF NAIADES 233 



Distribution of Colors as a Whole in Lake Brie (iii shells). 



Pearl Blue, etc 41% 



White, etc -- - 20% 



Light Pinkish Lilac, etc 27 % 



Pale Rhodonite Pink, etc 12 % 



Distribution in Lake Erie — Localities. 



La Plaisance Cedar Presque Maumee 



Bay Point Isle Drainage 



Pearl Blue, etc 10% 20% --.23% 20% 



White, etc - --33% - 3% 20% 16% 



Light Pinkish Lilac 50% 25 % 35 % 33 % 



Pale Rhodonite Pink, etc. 7% 47% 32% 31% 



Deductions from Tables of Percentages and PL III. 



Pearl Blue as well as white is more abundant in L. Erie, but the 

 Upper Ohio has more shades of Light Pinkish Lilac. Pink, however, 

 is a color comprised to large extent in Lake Erie shells, while pale 

 grayish blue violet is largely represented in the Ohio. 



In the Upper Ohio Drainage: 



Pinkish colors predominate in the Allegheny Tribs., but blues in 

 the rivers. 



There is less pink in the Ohio than in the Monongahela, while 

 white is not present in the tributaries of the latter. Pale Grayish 

 Blue Violet seems characteristic of the Beaver Tribs. as a whole, 

 while there is less pearl blue in the Ohio than in the Allegheny, but 

 more white. A fading out is seen going down stream in the Alleg- 

 heny, Monongahela, and Shenango Rivers as well as in the French 

 Creek. Characteristic stream colors are; 



Light Pinkish Lilac to Pearl Blue in the Allegheny, Pale Grayish 

 Blue Violet in French Creek, white with a Light Pinkish Lilac tinge 

 in Conewango Creek. 



In Lake Erie: 



Light Pinkish Lilac predominates at La Plaisance- Bay," while a 

 Lighter Pink represents Cedar Point. Presque Isle is apparently 

 between the two with regard to color, in this respect resembling 

 the Maumee Drainage. In this as well as in other species, character- 

 istic colors not mentioned for any given locality are obtained from 

 PI. III. 



Pale Persian Lilac is a typical color for shells from Conneaut 

 Lake, while a more pinkish variety of this — pale pinkish lilac — is 



