284 Mr. C. H. T. Townsend on Diptera 



species possessini^ the normal female will be known as 

 C. occidaaj 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 scuteUum shining black, with- 



out pollinose vittae, 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 .... 2. 

 Mesonotum with three pollinose vittae, scutellum 

 pollinose ; sides of front conspicuously silvery, 

 well defined ; abdomen black, with a median 

 vitta and two or three fasciae pollinose ; apical 

 cell shorter petiolate or closed in margin .... oceidua, Walk. 



2. Abdomen distinctly red on sides, especially an- 



teriorly ; third and fourth segments with polli- 

 nose reflections on each side hnmaculata, Macq. 



Abdomen wholly deep shining black, with or 

 without pollinose reflections on apical segment . PaUasii, Towns. 



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 f(nu'th segments 

 with pollinose reflections on each side immaculata, Macq. 



Williston's C. insuJaris, female, from St. Vincent, is ap- 

 parently a specimen of C. oceidua, Walk, (as restricted in the 

 table), with the median vitta obsolete on second segment. 

 His insulart's, male, is probably immaculata, Macq. 



C. melanosoma, Wulp, is, so far as can be said from a two- 

 line description, the same as PaUasii, the apical segment being 

 distinctly pollinose instead of obsoletely so. 



C. subpetiolata, Wulp, is a typical but small female of 

 oceidua, excepting only that the pollinose vitta and fascia of 



