THE CANADIAN ENTOMOLOGIST. 89 



sciitellum with long black bristles. Scutellum concolorous. Abdomen 

 yellowish-grey poUinose, with black hair ; a brownish-black median stripe, 

 interrupted at the incisures ; a pair of dusky spots on second and third 

 segments, and sometimes also on the fourth. Legs simple, blackish- 

 brown, except the yellow basal and immediate distal ends of femora and 

 basal ends of tibiae. Wings hyaline, somewhat dusky ; base orange 

 yellow. 



Female. — Front wide and with straight sides. Hind femora light 

 brown, except a subapical dusky band about one-third the length of the 

 femur in width. 



Nine males and ten females. The specimens are alcoholic, but in 

 excellent preservation. They are now in the museum of the University 

 of Kansas. 



The following differences between H. aids and H. serrata may be 

 noted : — The former is larger. It has thin black pile on the cheeks, while 

 in the latter the pile is golden and quite thick. The palpi of H. aids 

 are light-yellow in both sexes with no trace of black, except in the 

 scattered black hairs. The stripes on the dorsum of the thorax are much 

 more distinct. The legs differ considerably, being darker in colour ; in 

 the male they are blackish-brown, except the yellow basal and immediate 

 distal ends of the femora, and basal ends of the tibiae ; the female has 

 light brown hind femora varied by dusky bands near the distal ends. A 

 more important difference, however, is the lack of the serrations which 

 characterize the hind tarsi of the male H. serrata. Base of wings in the 

 present species more broadly and brightly yellow. 



Rondani defined the subgenus Lyperosia, to which H. serrata is 

 referred, from two characters, namely : hairs of arista all superior, and 

 anterior cross-vein opposite the termination of the first longitudinal vein. 

 An examination of my specimens of H. aids has discovered two with one 

 or two hairs on the underside of the arista ; and I may say, on the 

 authority of Dr. S. W. Williston, that the relation of the small cross -vein 

 to the end of the first vein in this and allied groups is very inconstant. 



I have compared the present species with the descriptions of European 

 species of Htzmatobia (except that of H. irritans which I did not have), 

 and find that H. ferox approached it in some respects, but, brief as is 

 the description, several important differences were noted. 



