HIPPOBOSCID^E. 151 



58. HIPPOBOSCIM;. 



Head flattened, usually attached to an emargination of the 

 thorax ; face short ; palpi wanting ; antennae inserted in pits 

 or depressions near the border of the mouth ; apparently one- 

 jointed, with or without a terminal bristle or long hairs. 

 Eyes round or oval, sometimes very small ; ocelli present or 

 absent. Thorax flattened, leathery in appearance ; scutellum 

 broad and short. Halteres small or rudimentary. Abdomen 

 sac-like, leathery in appearance, the sutures indistinct. Legs 

 short and strong, broadly separated by the sternum; tarsi 

 short; claws usually strong and dentated ; empodia usually 

 present. Wings present or absent. 



Not very many species of this singular family of flies are 

 known. They are all parasitic in the adult stage upon birds 

 or mammals. The larvae are pupigerous, but pass nearly the 

 whole of this stage within the abdomen of the parent, being 

 extruded when nearly ready to transform into the mature fly. 

 But a single puparium is extruded at a time and is of large 

 size. The flies have a peculiar, louse-like appearance, and 

 one often encounters them in handling recently killed birds, 

 especially the raptorial birds. They have a quick, short flight, 

 seeking the beard or hair of the collector, within which they 

 run nimbly, trying to hide. InLipoptena the wings are appa- 

 rently lost soon after the insect finds a permanent living place. 



I have united Strebla and its allies with this family, an 

 opinion shared by Professor Townsend, but have separated 

 them as a subfamily. I believe that their relationships are 

 closer here than with the Nycteribiidae. 



TABLE OF GENERA. 



1. Antennae small or indistinct; bead not sunken into the emarginate tho- 

 rax; wings large, with distinct, parallel veins and distinct outer 

 cross-veins ; claws short, simple. . ... . STKEBLIN^:. 



Antennae usually more elongate and the joints more or less distinctly 

 separated. Head sunk into an emargination of the thorax. Wings 

 when present without parallel veins, the weak veins running from 

 the strong costal veins outwards and backwards, the cross-veins 

 short,. and approximated to the base of the wing; claws large, biden- 



tate or tridentate HIPPOBOSCIN^. 



18 



