2 24 THE AMERICAN MIDLAND NATURALIST 



Characteristic stream colors appear to be, 



Pearl blue in the Loyalhanna, altho' a few are pink. 



Pinks and blues are apparently equal in the Shenango, altho' 

 these colors are seen to merge to a light grayish blue violet, the 

 pinks fading out. 



Pale flesh color in the Py ma tuning with a scattering of deeper 

 blues, (Plumbago blue). 



Pinks and blues seem equally distributed in Neshannock Creek. 



Pinkish colors in Slippery Rock Creek. 

 In L. Erie 



Lilac colors are characteristic at Presque Isle, Burn Blue at La 

 Plaisance Bay. 



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

 Males possess more pearl blues, less salmon colors, and a tendency 

 toward lilac colors not found in females. The latter have a pre- 

 ponderance of vivid pinks. 



5. — Symphynota (Lasmigona) costata. 



Here closest attention was paid to the color of the nacre in the 

 umbonal cavity, as apparently being the most variable. 



SIMPSON RIDGEWAY 



Whitish* Pearl Blue 



Straw colored Pale Pinkish Buff, Pale Ochraceous Buff. 



Sea-shell Pink, Pale Ochraceous Salmon 

 Light Buff, Pale Pinkish Buff. 



Distribution of Colors as a Whole in Upper Ohio Drainage and 

 L. Erie. (68 shells). 



Pale Pinkish Buff, etc 27 % 



Pale Ochraceous Buff, etc 23 % 



Sea shell Pink, etc 16% 



Pearl Blue ._ 16% 



Distribution of Colors as a Whole in Upper Ohio Draiiiage and 

 L. Erie. (47 shells.) 



Pale Pinkish Buff, etc.... 36 % 



Pearl Blue, etc 23% 



Sea Shell Pink, etc 17 % 



Pale Pinkish Cinnamon, etc - 10% 



Pale Grayish Vinaceous 4 % 



Pinkish Buff 10% 



*" Whitish" practically negligible in any part of the shell. Pearl Blue is 

 probably the real shade. 



