136 Annals Entomological Society of America  [Vol. XIV, 
group, Kirkaldy! states ‘‘the characters which appear to me to 
be of generic value in this section, lie in the genitalia and the 
tibial spur, though I am not prepared, without the examination 
of a large series of European and American forms, to formulate 
genera based on them.”’ Again referring to genitalia in general, 
Kirkaldy? further suggests ‘‘that the genitalia in the male are 
the final test of a species and even afford generic criteria.”’ 
Fieber®? appears to have been the first to use characters 
found in the pygofer, anal segment and genital styles for 
specific purposes and most workers, with a few notable excep- 
tions, have continued their use in certain groups of genera. 
Edwards! appears to have been the first to dissect and figure 
the aedeagus to distinguish certain allied species. Muir® 
in working out the Hawaiian Delphacide, placed greater weight 
upon the aedeagus and used the male genitalia not only for 
specific purposes, but also to rearrange the genera. He after- 
wards found other characters that confirmed his conclusions 
drawn from the genitalia alone. | 
In anticipation of using the genitalia in a similar manner 
Mr. Muir and the author are at present at work upon the 
North American and West Indian species. In the hopes of 
interesting students in these organs as characters of systematic 
importance, the following short description of the methods 
employed and the terminology decided upon, is presented. 
Morphologists may disagree with these terms and suggest 
using others that show the homology with other insects, but 
until we are sure. what those homologies really are it is best 
to use purely descriptive names, most of which are already in 
use. 
1Kirkaldy, Haw. Sug. Pl. Ass. Report 1907 Div. of Ent. Bull. III, p. 150. 
*Op. cit. page 124. 
3’Fieber Verhandl. Zool. bot. Ges. XVI, 1866, p. 517-534, Pl. ne 
4Edwards Hom. British Islands, 1896, pl. 6. 
5Muir Proc. Haw. Ent. Soc. III, 3, 1916, pp. 221, pls. 2, 3, 4. 
