BY ARTHUR WHITE. 257 



"blue-green, with two very long, widely-separated, marginal 

 black bristles. Abdomen brown, with small hindmarginal 

 black bristles ; hypopygium similarly coloured and fringed 

 with black pubescence. Legs with femora dark brown 

 above, yellow-brown below; tibiae and tarsi yellow-brown, 

 the tarsi apically darkened ; anterior and middle femora 

 almost bare, posterior femora, with a iTiw of rather long, 

 weak, black bristles; posterior tibias with shorter, but 

 staffer, black bristles; anterior tibiae, bare; middle 

 tibire with a few black bristles. Wings hyaline, with 

 dark veins. 



Female resembles the male very closely, but the third 

 antennal joint is. short and rounded, and the hgs ai^e 

 lighter. 



Of this species I have come across two specimens, a male- 

 taken on October 26, 1912, and a female, settled by the» 

 side of a pond, on April 26, 1914; from its small size it 

 is apt to be overlooked, and the species may not b© 

 uncommon. 



64. H Y D R p H o R u s, Fall. 



Wings having the last part of the poetical vein not. 

 longer than the posterior cross-vein; antennae xvith the 

 third joint rounded, and the arista doi'sal. 



Head as broad as, or a little broader than, the thorax; 

 vertex more or less excavated. Eyes well separated in 

 both sexes. Antennae situated rather high, all joints 

 short, but the third a little the longest, rounded apically, 

 and bearing a long, two-jointecl arista. Thorax with one 

 row of small acrostichal bristles, two rows of dorsocentral 

 bristles, and, on each side, a humeral, a, posthumeral, two 

 notopleural, and a postalar bristle, scutellum wHh four 

 marginal bristles. Abdomen short, the hypopygium ol 

 the male almost concealed, and not recurved beneath the 

 venter. Legs of medium length, and frequently showing 

 sexual characters; femora and tibiae with bristles. Wings 

 rather long and narrow, sometimes spotted, the last part 

 of the postical vein (i.e., the part from the discal cell to> 

 the wing-margin) very short, and not longer than the 

 posterior cross-vein, so* that the discal cell is very long, and 

 approaches close to the wing-margin. 



The species belonging to this genus are confined to the 

 neighbourhood of water, on the surface of which most of 

 them are able to run. A Tasmanian species, which is; 

 unknown to me, was described by Maequart. 



