VARIATION IN NACREOUS COLOR OF NAIADES 225 



Distribution of Colors in Upper Ohio Tributaries, etc. 



Allegheny Allegheny Beaver 



Tribs. River Trips. 



Pale Pinkish Buff, etc 10% 17% 28% 



Pearl Blue, etc 20%. .8%.. 14% 



Sea Shell Pink, etc 10% 17% -8% 



Pale Pink Cinnamon, etc 15% i7% ^4% 



Pinkish Buff, etc... 10% 8% 



Pale Salmon, etc.... 10% - 2 1 % 



Pale Ochraceous Buff 10% 21% 



Ochraceous Buff 10% 



Light Grayish Blue Violet, etc 8% 



Pale Grayish Vinaceous, etc.... ....8 % 



Salmon Buff.. 8% 



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



Pale Ochraceous Buff, etc 34% 



Pale Ochraceous Salmon, etc.. 38 % 



Light Buff, etc - 9% 



Pale Pinkish Buff, etc --i9% 



Distribution in L. Erie — Localities 



Presnue La Plaisance 



Isle Bay 



Pale Ochraceous Buff, etc 33 % 



Pale Ochraceous Salmon, etc 2>2> % 



Light Buff, etc 50% 



Pale Pinkish Buff, etc 11 % 



Pale Salmon, etc.. 11 % 50% 



Pale Cinnamon Pink, etc... 11 % 



Pinkish Buff, etc....... 11 % 



Deductions Jrom Tables of Percentages and PI. III. 



As previously noted, the greatest attention was paid in this 

 species to the color of the umbonal cavity. Shell for shell, the blues 

 seemed deeper in the rest of the nacre in L. Erie, altho' more pearl 

 blue as a color of the umbonal cavity is reported from the Upper 

 Ohio. Buff and salmon colors preponderate in L. Erie, where in 

 the Upper Ohio, the colors may be pearl blue or pinkish. 

 In the Upper Ohio Drainage: 



Shells lose their buff colors and become pink going down the 

 Allegheny. This also occurs in French Creek, and seems to be the 

 case also in the Monongahela River and possibly in the Shenango. 

 As a general rule there seemed to be more purely pearl blue in the 

 Allegheny Tribs. than in the river itself. Other characteristic 

 stream colors, besides those shown on PI. IIII are, 



Ochraceous Buff in Quemahoning Cr. 



