284 Mr. C. H. T. Townsend on Diptera 
species possessing the normal female will be known as 
C. occidua, Walker. Loew’s name divisa will remain a 
synonym of the latter. It is to be borne in mind that the 
form with the aberrant (dimorphic or male-like) female was 
described in the male by Macquart. The form with the 
normal female was described in the female by Walker, and 
later in the male by Loew. Therefore it is clear enough that 
Walker’s name must stand. 
As this subject has become somewhat complicated, I intro- 
duce the following table of males and females of Cistogaster 
known to me, which will remove all doubt and possible mis- 
understanding with regard to the separation of these species. 
Table of Cistogaster. 
Females. 
1. Mesonotum and scutellum shining black, with- 
out pollinose vittee, only the humeri pollinose ; 
sides of front shining black, hardly at all sil- 
very ; abdomen without distinct pollinose vitta 
or cross-bands, apical cell longer petiolate . 
Mesonotum with three pollinose vitte, scutellum 
ollinose ; sides of front conspicuously silvery, 
well defined ; abdomen black, with a median 
vitta and two or three fascize pollinose ; apical 
cell shorter petiolate or closed in margin .... occedua, Walk. 
Y. Abdomen distinctly red on sides, especially an- 
teriorly ; third and fourth segments with polli- 
nose reflections on each side ..........-....- zmmaculata, Macq. 
Abdomen wholly deep shining black, with or 
without pollinose reflections on apical segment. Pallasi, Towns. 
bo 
Males. 
A longitudinal fuscous stripe on abdomen in con- 
nexion with the median pollinose vitta ; abdo- 
men bright ferruginous, third and fourth 
segments more or less pollinose ............ oceidua, Walk. 
Fuscous stripe of abdomen wanting, the median 
pollinose vitta more or less distinct; abdomen 
more yellowish, the third and fourth segments 
with pollinose reflections on each side........ tmmaculata, Macq. 
Williston’s C. insularis, female, from St. Vincent, is ap- 
parently a specimen of C. occidua, Walk. (as restricted in the 
table), with the median vitta obsolete on second segment. 
His znsularis, male, is probably ¢mmaculata, Macq. 
C. melanosoma, Wulp, is, so far as can be said trom a two- 
line description, the same as Pallasz7, the apical segment being 
distinctly pollinose instead of obsoletely so. 
C. subpetiolata, Wulp, is a typical but small female of 
occidua, excepting only that the pollinose vitta and fascia of 
