CERTAIN TAXONOMIC CHARACTERS OF GRYLLUS. 



15 



POST H.RIOR F F.MORA 



o io rr 12 1314 151617 



the entire generic range. Fig. 5 presents the same idea in another 

 form. In it are given the regression lines of the posterior femora on 

 the ovipositor for the genus as a whole and also for three local collec- 

 tions of Gryllus from widely separated areas. The lengths and positions 

 of these lines show the range of variation in the different collections 

 and also the relative proportions of the ovipositor and the posterior 

 femora in each. As previously stated, this relation is important from a 



taxonomic standpoint. It is 

 apparent that while there 

 are differences between the 

 various regression lines, the 

 general trend of regression 

 is the same, not only in local 

 samples of the genus, but in 

 the genus as a whole. 



As would be expected, no 

 one local collection presents 

 as wide a range of variation 

 as the genus as a whole, but 

 the relative amount of varia- 

 tion seems to me surprisingly 

 large. In table 8 I give the 

 average coefficients of varia- 

 tion as found in the Maine, 

 Massachusetts, New York, 

 and Florida collections, and, 

 for comparison, the inter- 

 specific coefficient of varia- 

 tion. The coefficients for the 

 body-length are here includ- 

 ed merely for completeness, 

 because taxonomists often 

 make use of this character. 

 I consider the body-length 

 constants of very little im- 

 portance in a study of varia- 

 tion, as the length of the 

 body is dependent upon factors of no evolutionary interest, such as the 

 size of recent meals or, in the case of the females, the number of unlaid 

 eggs. Considering the other organs, there is a striking parallelism be- 

 tween the intraspecific and the interspecific coefficients of variation with 

 respect to the relative variability of these organs. The data indicate 

 that both in the short-winged portion of the genus as a whole and, on the 

 average, in local collections of short-winged Gryllus,ihe tegmina are 



O 

 k 

 s 



^ 

 O 



Qs 

 s 



9 



10 

 ii 



12 



'3 

 14 



15 

 16 



i? 

 18 



19 



20 

 21 

 22 



23 

 24 



FIG. 5. Intraspecitie and iiitt.-rspw.ilic regression Hues of 

 posterior femora on ovipositor. Solid lines, short- 

 winged groups; broken, long-winged, a b aud a c, 

 Gotha, Florida.; d c, Perkins C'ove, Maine.; />/, base of 

 spit, Cold Spring Harbor, New York. The other pair 

 are the interspecific regression lines-. 



