102 
Psyche 
June- August 
THE genus CYRTOPOGON (DIPTERA; ASILIDtE)^ 
By a. L. Melander. 
In the elaboration of Osten Sacken’s table of Cyrtopogon 
given in Back’s 1909 study of Robber-flies thirty species are 
included. This genus is particularly well represented in the 
Pacific States and several new forms have been discovered by 
western collectors since the publication of Back’s review. Ac- 
cordingly the following indentification table is appropriate to 
bring to date our knowledge of this group of especially in- 
teresting flies. References are given in the table to those species 
described since Back’s paper was published. 
Many of the species of Cyrtopogon exhibit sex dimorphism. 
This is particularly the case with those species having red an- 
tennae. At times the males and females look quite unlike. The 
males present easy recognition characters in their elaborate and 
brilliant sex attire, but sometimes the more modest appearing 
females of several species resemble each other so closely as to 
be differentiated with difficulty. 
The characters used in the table are for the most part reason- 
ably constant. There is some individual variation in the color 
of the legs and of the hairs of face, hypopleurse, scutellum, ab- 
domen and legs, and in the extent of interruption of the ab- 
dominal fasciae. Where such variations have been sufficient 
to cause doubt in interpreting the table, cross-references have 
been introduced for more accurate guidance. Types of the new 
species are in the writer’s collection. 
Key to the Species of Cyrtopogon. 
1. Scutellum convex, generally long-pilose, usually shining 
or with touch of pollen at base, rarely pollinose among 
the species with long arista 2. 
Scutellum flattened and uniformly and quite densely pol- 
linose ; antennae black 32. 
iContribution from the Zoology Laboratory of the State College of Washington. 
