10 
Indiana University Studies 
the variable elements of other species or subgenera. It is 
only in small part true that certain characters furnish the 
basis for subgeneric, others for specific, and still others for 
varietal distinctions, and we must discard this much-used 
idea if our classifications are to show anything like evolution- 
ary relationships. A certain few characters, however, are the 
ones which vary most often; these are the size of the eye, 
the antennal and leg coloration, the mesonotal and mesopleural 
sculpturing, the size of the areolet, and the total length of 
the insect, and these in general furnish the most diagnostic 
characters. In a few instances, however, as with the areolet 
in the species irregidaris, these very characters are the ones 
showing so much individual variation that they are worthless 
for taxonomic use. The males are in every case more distinc- 
tive than the females. Much of the preceding data will have 
added interest upon the publication of the corresponding data 
for other cynipid genera, when, I may now suggest, some 
amount of agreement and some disagreement will be found 
as to the nature of variation within different groups. 
The degree of similarity of the females and males is 
considerably different in the several species. Thus the aver- 
age number of characters in which the males differ from 
the females is 
9 (6-10) for Dolichostrophus. 
7 for Neospatheg aster. 
5 (4-7) for Diplobius, 
There is a noteworthy difference between the close similarity 
of the sexes in a species like vernus or niger, and the con- 
siderable disagreement in irregularis. In practically all of 
the varieties of a species there is the same amount of second- 
ary sexual diversity, but in N. vesicula cerinus and N. niger 
alimas there is more diversity than is found in the other 
varieties of those species. 
This morphologic variation data should be compared with 
the variation shown by that part of the physiology of the 
insect which is reflected in the gall structure. 
Subgenera insects vary considerably, galls moderately. 
Dolichostrophus insects vary moderately, galls slightly. 
Diplobius insects vary slightly, galls considerably. 
Variety insects vary slightly, galls only rarely. 
