VARIATION IN NACREOUS COLOR OF NAIADES 23 1 



Observation on Sex Correlative Coloration, etc. (j shells). 



Males tend toward lavender colors, females blue. In this species, 



as well as a few others dealt with, the numbers used hardly 



justify any definite conclusion as to the association of nacreous 



color with the sex of the animal. \ 



10. — Eurynia recta. 



SIMPSON RIDGEWAY 



Purple Light Pinkish Lilac, Light Purplish Vinaceous, 



Pale Congo Pink. 

 Bluish White Pearl Blue 



Whitish White 



Distribution of Colors as a Whole in the Upper Ohio Drainage 

 and Lake Erie. (54 shells). 



Pearl Blue, etc 33% 



White, etc.... 21% 



Light Pinkish Lilac, etc 30% 



Light Purplish Vinaceous, etc 15 % 



Distribution of Colors as a Whole in the Upper Ohio Drainage 

 iS3 shells). 



Pearl Blue, etc 32% 



White, etc 24% 



Light Pinkish Lilac, etc... 23 % 



Light Purplish Vinaceous, etc 21 % 



Distribution of Colors in Upper Ohio Tributaries, etc. 



Alleghney Alleghney Ohio Tuscarawas 



Trtbs. River River River 



Pearl Blue, etc 34% 31% 36% 60% 



White, etc -i6% .24% 36% 



Light Pinkish Lilac, etc 37% 20% 16% ...20% 



Light Purplish Vinaceous, etc ....17% 25% 12% 20% 



Distribution of Colors as a Whole in^Lake Erie. (21 shells). 



Pearl Blue, etc 39% 



Light Pinkish Lilac, etc 30% 



Light Purplish Vinaceous, etc.. 21 % 



Pale Congo Pink, etc 12 % 



Distribution in Lake Erie — Localities. 



Cedar Point Pesque Isle 



Pearl Blue, etc -50% 36% 



Light Pinkish Lilac, etc 2,7, % 34% 



Light Purplish Vinaceous, etc 17 % 20% 



Pale Congo Pink, etc 10% 



Deductions from Tables of Percentages and PI. III. 

 A greater amount of Pearl blue and light purple exists in Lake 



