THE AMERICAN NATURALIST. [Vol. XXXVIII. 



The Auburn Shells. 

 Figure 2. 



The Auburn shells are not as variable as those from Roches- 

 ter, a fact shown by the greater regularity of the curve, which 



is practically bimodal, the minor mode being at 54 per cent, with 

 a frequency of 21 and the major mode at 57 with a frequency 

 of 24. The data for this curve is shown in Table B. 



Table B. 



56 57 58 59 60 6_i 62 63 



T 2^ 76 T y 4 I 3 



le number of shells examined was 104. The range of vari- 

 is from 45 to 79 per cent. 



45 50 53 54 5_5 

 r I 5 21 3 

 64 65 66 68 79 



