28 



THE VARIATION AND CORRELATIONS OF 



furnishes abundant food and protection to crickets. The cove is, fur- 

 thermore, protected from the majority of the winds, but receives full 

 benefit of the sun's heat. Thus there is here a sort of an island of 

 favorable conditions in the midst of quite unfavorable ones. Indeed, in 

 the country just outside of this small cove Gryllus was so scarce as 

 to be practically absent. I was very much surprised to find 22 macrop- 

 terous females and 4 macropterous males in this collection. They were 

 brought back alive to be used in breeding experiments. 



The seriations of the short-winged females are given in table 14. 

 For the reasons stated on page 15 I did not make measurements of the 

 body-length for the entire collection; 20 individuals, picked at random, 

 had an average body-length of 23.4 (range, 20.75 to 27.25). 



TABLE 14. Variation curves of the Perkins Cove collec1i<i. 



The constants of these curves are shown in table 15. 



TABLE 15. Variation constants of the Perkins Cove collection. 



The correlations existing between the lengths of these organs are 

 shown in tables 17 to 22. The coefficients calculated from these are 

 given in table 16. 



TABLE 16. Coefficients of correlation of the Perkins Cove collection. 



