4 THE VARIATION AND CORRELATIONS OF 



under great obligations. I wish also to thank, at this time, those who 

 have helped me to secure data. That part of these data which is used 

 in the present discussion, together with the constants calculated from 

 them, are given in the Appendix. Unless otherwise stated all the 

 measurements are from mature females. 



1. THE TAXONOMY OF GRYLLUS NATIVE TO EASTERN UNITED STATES. 



De Vries (1904) considers that specific characters are usually sharply 

 defined against one another. They are, according to him, separate 

 qualities more often than different degrees of the same quality. This 

 is not true of the crickets, as they are now named. One species does 

 not possess "units" which the others of the same genus lack, but one 

 species differs from the others merely in the "degree" of common 

 characters. Presence or absence of characters (e. y. , mobility of tibial 

 spines, teeth between these spines, etc. ) are considered of generic or 

 higher value. 



Davenport & Blankinship (1898) have expressed the expectation that 

 biometry would furnish us with a "precise criterion of species" and 

 would, in part at least, clear away the haziness which exists in the 

 taxonomy of most orders of both plants and animals. This haziness is 

 most pronounced where species are based, as they are in the Gryllinse, 

 upon differences in size of characters common to the different species, 

 and not upon de Vriesian "units." When starting this work I hoped 

 that a statistical study of relatively large collections might bring out 

 several sharply defined groups upon which we could logically fix specific 

 names. The extremely frequent appearance of "Gryllus sp. " in other- 

 wise detailed taxonomic lists emphasizes the need. 



De Saussure, one of the foremost taxonomists of the genus, gave up 

 sharply defining the limits of his own species. 



Beutenmiiller (1894), considering the crickets of New York and vicin- 

 ity, groups luctuosus, nigra, and neglectus with pennsylvanicus; and 

 angustus with abbreviatus. As I understand it, he is still of the opinion 

 that we have in northeastern United States only these two species, and 

 that their distinguishing mark is the long ovipositor (18 to 21 mm.) of 

 abbreviatus as compared with the short one (12 to 15 mm.) of pennsyl- 

 vanictix. The former is more apt to occur in sandy places and to 

 mature in the spring. 



Lochhead (1897) was unable to see any difference between abbreviatus 

 and pennsylvanicus, although he worked over a large variety of char- 

 acters, including wing venation. However, fixing upon the fact that 

 "one form, luctuosus, has hind wings which project like tails behind 

 the wing-covers," and that this character occurs in both sexes, he was 

 inclined to call this form a distinct species and to refer everything else 

 of this region to abbreviatus. This idea is founded upon a mistake, for 



