THE SYSTEMATIC VALUE OF THE MALE GENITALIA 
OF DELPHACIDZ (HOMOPTERA). 
By WALTER M. GIFFARD. 
During the past three years the writer has had an exceptional 
opportunity to study the male pygofer and genital organs of 
large collections of Dephacidae, including many types and 
paratypes, representing most of the species described from 
North America and the West Indies. Because of their con- 
stancy and reliability as a specific character these organs 
(which of course include the aedeagus or penis) are unques- 
tionably of first importance to the student in making correct 
determinations. The use of color as a specific character has 
led to synonomy on account of there sometimes being four color 
forms in a species, the sexes of both the brachypterous and 
macropterous forms being different. And among these forms 
there is often considerable color variation. This naturally 
results in much perplexity to the student of these insects. 
There have been and there are still strong objections by 
some workers (perhaps rightfully so) to base generic determina- 
tions on any one constant character, these preferring to accept 
a natural assemblage of characters from which to found the. 
genus. A close examination and study -of the collections 
previously referred to revealed in each of the genera (taking the 
genotype itself or its congeneric representative as a guide) a 
marked similarity in the form and character of the male genitalia: 
within each genus, so that each of the genera studied could in a 
very large measure be determined at a glance by the structure 
of the pygofers and of the exposed genital organs alone, without 
recourse to other external characters. Within certain genera, 
as they stand at present, two or more types of genitalia are 
present and the question arises if such sexual characters, found 
only in one sex, should be used to erect new genera. In such 
cases it is highly improbable that the genus is monophylogenetic. 
In the erection of genera the hind tibial spur or calcar has not 
been considered as much as it should have been, even by 
Kirkaldy, Muir and Crawford, who have used it for subfamily 
and tribal divisions. In discussing the Liburnia (‘‘ Delphax’’) 
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