VARIATION IN NACREOUS COLOR OF NAIADES 227 



buff colors. Lavenders and grays predominate in the Upper Ohio 



Drainage. 



In the Upper Ohio Drainage: 



In the headwaters of French Creek this shell is pearl blue, 

 lower down becoming pale grayish blue violet. In the 

 Shenango, it fades out from a pale pinkish cinnamon color in up- 

 stream regions to pale grayish blue violet downstream. Fading out 

 is also observed in the Crooked Creek Drainage. Characteristic 

 stream colors are, 



Sea-shell pink in the Mahoning. Pearl blue in Slippery Rock and 

 Racoon Creeks, Vinaceous pink in Sugar Creek, Pearl Blue in 

 Tuscarawas River, Pale Grayish Blue Violet in the Maumee 

 Drainage. 



Shells from Conneaut Lake resemble those of L. Erie to some 

 extent in possessing a light pinkish lilac hue. 

 In L. Erie: 



Characteristic hues as shown. 



Observation on Sex Correlative Coloration, etc. {8 shells). 



Males have a pearl blue or cream color. 

 Females — pale grayish blue violet or pinkish. 



7. — Paraptera fragilis 



SIMPSON RIDGBWAY 



Faint Purplish Pale Pinkish Lilac, Pale Congo Pink 



Bluish Pearl Blue. 



Distribution of Colors as a Whole in Upper Ohio Drainage and 

 L. Erie. (58 shells). 



Pearl Blue, etc 20% 



Pale Pinkish Lilac, etc , 50% 



Pale Congo Pink, etc 30% 



Distribution of Colors as a Whole in the Upper Ohio Drainage 

 (28 shells). 



Pearl Blue, etc 20% 



Pale Pinkish Lilac, etc _ 40 % 



Pale Congo Pink, etc 40% 



Distribution in Upper Ohio Tribs., etc. 



Alleghenv Ohio 



River River 



Pearl Blue, etc 10% 15% 



Pale Pinkish Lilac, etc 55 % 



Pale Congo Pink, etc 90 % 30 % 



