VARIATION IN THE VENATION OF 
TRIMEROTROPIS. 
JEROME McNEIL. 
A. RECENT study of nearly all the known species (fifty out of 
fifty-four) of the orthopteran genus Trimerotropis has afforded 
the writer an opportunity to note the amount of variation which 
occurs in the venation of the tegmina and wings of a single 
genus. Three out of the four subfamilies of Acrididz found 
in North America north of Mexico, z.e., Acridine, Tryxalinze, 
and CEdipodinze, present but a single and little modified type of 
venation well represented by the 7”. vinculata Scud (Figs. 1, 2). 
The remaining subfamily, Tettiginz, is so extremely differ- 
ent as to show little relationship to Acrididz. In all the draw- 
ings the terminology used is that of Comstock and Needham, 
with the very slight modifications necessary to adapt it to 
Orthoptera. The homologies have been determined by the 
writer from a study of the tracheation of the tegmina and 
wings of nymphs, which is to be published shortly. 
It will be noticed by those familiar with this nomenclature 
that the branches of X. have been named as if they were acces- 
sory branches entirely, whereas it is very probable that some 
of them represent the primary forks of that vein. At present 
it is impossible to be quite certain of these homologies, so that 
the simplest way of naming them has been employed without 
claiming for it complete accuracy. 
VARIATIONS WITHIN A SPECIES. 
For the purpose of studying the variation within the limits 
of a single species I have selected 77. saxatilis McN., a species 
from Arkansas and southern Illinois, and one of the three spe- 
cies known to occur east of the Mississippi. This form was 
not selected because of its being unusually variable in venation, 
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