98 EMPID^. 



ments. Legs slender, almost equal in length. Coxae shorter than the 

 femora. 



Male. Eyes more contiguous than those of the female. Abdomen 

 cylindrical, compressed and recurved at the tip. Fore metatarsi most 

 often dilated. 



Fern. Eyes more remote. Abdomen oblong-, pointed at the tip. 

 Fore metatarsi slender. 



The Hilarae feed on smaller insects, chiefly on Diptera, and 

 also on the nectar of flowers. They assemble in swarms, and 

 dance together over water during the fine summer evenings ; 

 sometimes myriads may be seen near the surface of a river, flying 

 in continual succession and in opposite directions, and appearing 

 like a stream of light. " The myriads of Hilarte, which fill the 

 air over rivulets hi summer, form a pretty spectacle. Their 

 evolutions in the air are graceful and regular. At one time they 

 revolve in circles, horizontal or oblique, so that the spectator sees 

 two or more streams crossing each other, and seeming to inter- 

 lace. At another time, without perceptible cause, the whole 

 multitude sweep away simultaneously in one direction (as if a 

 rush of wind had borne them off), and then return more leisurely 

 to their former station. . It is difficult to single out any indi- 

 vidual among the multitude, so as to trace its course." 

 Haliday, MSS. The genus may be thus divided : 



a. Fore metatarsus of the male incrassated. Species 1-19. 

 a a. Fore metatarsus of the male simple. Species 20. 



1. cilipes, Mg. zw. iii. 3. 1 (1822) ; Ct. ! b. e. 130. Nigro- 

 cinerea t antennis nigris, alia fuscis, halteribus fuscis basi fulvis, pedibus 

 nigris, genubus ferrugineis. Long. 2 ; alar. 5 lin. 



Greyish-black, hairy. Proboscis, palpi, and antenna? black. Wings 

 brown ; stigma blackish ; veins black, tawny at the base. Halteres 

 brown, tawny towards the base. Legs black ; knees ferruginous. 

 Male. Fore metatarsus and following joint dilated, clothed with long 

 black hairs. 



Generally distributed. (E. S. I.) 



2. matrona, Hal. e. m. i. 158 (1833). spinipes, Ztt. Nigricans, 

 alis fumatis, halteribus et femoribus luteis ; Mas. metatarso antico 

 dilatato elliptico, margine ciliato. Long. 2 ; alar. 5^ lin. 



Black. Wings blackish-brown ; stigma darker. Halteres, coxae, 

 femora, and half of fore tibia, as well as the base of the posterior tibiae, 

 dingy yellow. Male. Fore metatarsus and following joint dilated, 

 clothed with long black hairs. 



Rare. In Mr. Haliday's collection. (I.) 



3. maura, Fb. s. i. ii. 471. 4 (1781); FJn. ; Mg.; Zii.globu- 



