150 BLEPnAROCERIDTE. 



The autennse are composed of the usual two basal (scapal) joints- 

 and a usually elongate cylindrical flagellum of from nine to fifteen 

 joints, which are shortly pubescent. In some genera the flagellum 

 is shorter and relatively more robust. 



Body practically bare ; thorax with transverse suture distinct, 

 broadly interrupted. The abdomen slender, geuei-ally of uniform 

 width. The male genitalia reach their greatest complexity in 

 BibiocephaJa, and are most simple in Blepharocera. In the former 

 the principal pair of claspers is two-jointed, the second joint repre- 

 sented by two elongate, pliable, finger-like pieces. There are 

 apparently (judging from Kellogg s plate) two other pairs of sub- 

 conical elongate claspers ; a small ventral plate, bi-emarginate on 

 the posterior margin, and an intermediate, rather robust organ. 

 The female genitalia consist mainly of a pair of small rather 

 blunt lamellae. 



The legs are long and slender, the hind pair much longer than 

 the others. In some species the fore femora are curved in the 

 male; the tibiae may or may not possess terminal spurs; the 

 claws small, and the empodia small or rudimentary ; pulvilli 

 absent. 



Venation generally incomplete. The auxiliary and 1st longi- 

 tudinal veins are united, unless one or the other is considered to be 

 absent. The 2nd longitudinal vein is simple or forked ; when the 

 latter, the forking always occurs towards the tip ; 3rd longitudinal 

 vein present or absent ; in the latter case the anterior cross-vein 

 connects the 2nd and 4th longitudinal veins. Anterior cross-vein 

 generally present, often appearing to be the origin of either the 

 2nd or the 3rd vehi. The 4th longitudinal vein a])parently always 

 present ; a lower branch of it often present, but with the basal 

 half of this branch obliterated. This is what Kellogg calls an 

 incomplete media. The 5th longitudinal vein present, simple or 

 forked ; posterior cross-vein present or absent ; 6th longitudinal 

 vein present or absent. No discal cell. 



As to cells : in the genus PJiiloris, in which the venation reaches 

 its greatest development, there is a costal cell, marginal, sub- 

 marginal, 1st, 2nd and 3rd posterior cells (the 2nd being distally 

 divided by the incomplete branch of the 4th vein) ; an anal and 

 an axillary cell. Anal lobe of wing generally well developed, often 

 exceptionally so (Philorus, Bihiocephala, Blepharoccra) ; sometimes 

 it is absent (Paltostoma). Alulae, properly speaking, absent, 

 tegulae always absent. Halteres well developed. 



Life-history. The larvae of all known species live in clear, 

 running, highly aerated strennis, where they fix themselves with 

 great tenacity to the sides of the rocks, prei'erring those spots 

 M'here the stream flows fastest, and tliey occur almost exclusively 

 in mountainous or hilly regions. They travel slowly and mainly 

 in a lateral or sideways dii'ection. The larva consists of a head 

 segment (which is composed of the fused head and three thoracic 

 segments united), and five body segments, the last one formed of 

 the two anal abdominal segments united, but -udth an intervening 



