HOUGH. 



[VOL. i. 



The two species are easily separated by the following points : 

 hind tarsi of male serrate in serrata, not so in aids; palpi 

 black in s errata, yellow in aids ; pile of bucca black in aids, 

 yellow in serrata; at cephalo-dorsal angle of mesopleura aids 



FIG. 2 a. 



has a large macrochaeta curved 

 dorsad ; serrata has no macro- 

 chaeta at this point ; at the 

 cephalo-ventral angle of the 

 mesopleura (protecting the pro- 

 stigma) aids has two small bristles ; serrata has a tuft of golden 

 yellow hairs ; serrata has much longer and denser pile on the 

 dorsum of the thorax. Other color differences are pointed out 

 by Professor Snow in connection with his description of aids 

 in Can. Ent., April, 1891. I am much indebted to the Ento- 

 mological Department of Kansas 

 University for a pair of speci- 

 mens of H. aids which have 

 enabled me to ascertain the im- 

 portant differences in the chae- 

 totaxy of the mesopleurae above 

 mentioned. 



HcniicJilora. - - Only known species and type of genus H. 

 vittigcra Bigot, Mexico. Professor Williston, in his Manual 

 of North American Diptcra, p. 143, suggests parenthetically 

 that this may be the Idia viridis of Wiedemann (Auss. Zivdf., 

 Vol. II, pp. 354, 11). I quite agree with this suggestion for 

 the following reasons. Meigen founded the genus Idia in 1826, 

 and in his characterization (Syst. BescJir. Eur. Zwdf., Vol. V, 

 p. 9) the only distinguishing character is the pectinate arista. To 

 this Wiedemann (loc. dt., p. 347) adds : face prolonged forwards 



FIG. 2 b. 



