54 



THE NAUTILUS. 



These comparisons show that the average number of ribs of 

 the blue Pecten at Atlantic City is less than the same species 

 at Cold Spring Harbor but about the same as at Fire Island 

 and Cutchogue. That they are more variable than any of 

 these that Davenport reported is also shown by the statistics. 

 To determine the significance of these differences will require 

 much more work. 



The author wishes to thank Dr. E. F. Phillips for his share 

 in the work, and also for first introducing him to modern 

 statistical methods. 



Literature. 



Davenport, C. B. 1900. On the Variation of the shell of 

 Pecten irradians Lamarck, from Long Island. Am. Nat. 

 XXXIV, pp. 863-877. 



Davenport, C. B. 1903. A Comparison of the Variability 

 of some Pectens from the East and the West Coast of the 

 United States. Mark Anniversary Volume, pp. 121-136, 

 New York, Henry Holt. 



Davenport, C. B. 1903. Quantitative Studies in the Evo- 

 dution of Pecten opercularis from three localities of the 

 British Isles. Proc. Am. Acad. Arts and Science XXXIX, 

 pp. 123-159. 



Davenport and Hubbard, M. E. 1904. Ray Variability 

 in Pecten varius. Jour. Exp. Zool., Vol. 1, p. 607. 



Davenport, C. B. 1904. Statistical Methods. Wiley & 

 Sons, New York. 



