QQ C. II. TYLER TOWNSEND. 



Described from one specimen. Las Cruces, N. Mex., June 3 ; on 

 flowers of Aster spinosus. This may be the male of H. celcr. 



42. Gymiiosonia f uligiiiosa R. D. 



I believe this to be distinct from the European G. rotnndata L., 

 after comparing three males of the latter with a series of the Amer- 

 ican males. The Euro])ean male has the face more silvery, and the 

 antennjB almost entirely black. The American male has the fiice 

 with a brassy tinge, and the antennae very largely fulvous. 



The European s^^ecimens were kindly sent me by Mr. v. d. Wulp 

 and Mr. v. Roder. 



While on the subject of the genus Gyninoxoma, it may be well to 

 point out that Macquart (Dipt. Ex. Sup. ii, 81) records the occur- 

 rence of.G'. rotHiidata Wg. (so identified by him) from Tasmania, 

 saying, also, that it exactly resembles the European form. This, 

 therefore, gives Gymiiosoma a range in the southern Hemisphere, but 

 in the temj^erate regions. It is not a tropical genus. I doubt Mac- 

 quart's specific determination, however. 



43. Cistogrtster iiniuaciilata Meq., Dipt. Ex. ii, 3, 76. 

 Gyninosoma occidua Wlk. and Cistogaster divisa Lw. are synonyms 



of this species. Macquart and Loew described the male, and Walker 

 the female. 



In connection with this species, there is an interesting point to be 

 decided. Having examined an extensive series of Cldogader, which 

 I believed to belong to this one species, although there was much 

 variation among the females, I found that I could readily separate 

 the individuals of the latter sex into two constant series. As there 

 did not seem to be any constant differences in the males, in fact very 

 little variation if any, it occurred to me that there might be a case 

 of dimorjihism among the females of this species, the normal form 

 being that described by Walker, and also by Williston (Trans. Am. 

 Ent. Soc. xiii, 296). This form has the mesoscutum shining black, 

 with three distinct white pollinose vittse (scutellum pollinose), the 

 abdomen with a median similar vitta and two or three similar cross- 

 bands or fascise, and is larger than the male. The other form of the 

 female approaches the male in both size and the color of the abdo- 

 men, having the latter more or less red, especially anteriorly on the 

 sides, the rest blackish, but not showing the cross-bands or median 

 vitta more than in the male ; the principal difference, however, is in 

 the color of the mesoscutum (including the scutellum), which -is 



