LXI. FAMILY NYCTERIBIID^S. 



Small, spider-like, wingless flies. Head oval, folding 

 back when at rest in a groove on the dorsum of the tho- 

 rax. Antennae short, two-jointed, the oval terminal 

 joint with bristles inserted in tubercles. Eyes and ocelli 

 vestigial. Thorax depressed, laterally anteriorly with 

 comb-like bristles. Abdomen oval, with more or less 

 distinct segmental scutes. Legs long, the knees at rest 

 prominent above the thorax. Femora broad; tibiae club- 

 bed or shovel-shaped; metatarsus very long. Halteres 

 pedunculate or sessile, in the latter case often indistinct. 



This family includes a considerable number of species, 

 distributed widely in different parts of the world, all of 

 them parasitic upon bats. Various attempts have been 

 made to divide the group into smaller genera, but not 

 with much success, Nycteribia being the only well defined 

 genus known. Penicillidia differs in the more aborted 

 and sessile halteres, and the species are of larger size, 

 but I doubt its validity. 



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