152 NORTH AMERICAN DIPTERA. 



STREBLINJE. 

 1. Eyes small, situated on the posterior angles of the head. 



STREBLA Wiedemann. 

 Eyes situated near the middle of the head (Mexico). 



TRICHOBIUS Townsend. 



HIPPOBOSCIN.E. 



1. Claws tridentate 2 



Claws bidentate 3 



2. Wings rudimentary ; ocelli wanting. BKACHYPTEROMYIA Williston. 

 Wings large, functional; ocelli present. ORNITHOMYIA Latreille. 



3. Wings wanting or rudimentary, in the males at least. ... 4 

 Wings present, functional, 5 



4. Eyes very narrow and situated on the sides of the head ; no ocelli. 



MELOPHAGUS Latreille. 



Eyes larger, oval; ocelli present, but sometimes indistinct; wings ca- 

 ducous in one or both sexes. . - . LIPOPTENA Nitsch. 



5. Antennae short, tuberculiform. . . . HIPPOIJOSCA Linne. 

 Antennas elongate, clothed with hair distally. . OLFERSIA Leach. 



59. NYCTERIBIID^E. 



Head small, capable of being turned backward into a groove 

 on the dorsum of the thorax. Antennae short, indistinctly 

 jointed, the terminal joint oval, with short hairs. Eyes and 

 ocelli indistinct or wanting. Legs long, the femora and tibiae 

 flattened. Tarsi arcuate. No wings. 



These peculiar flies, like those of the foregoing family, are 

 pupiparous. They live exclusively on bats. But little is 

 known of their early 'stages. (See Osten Sacken.) The flies 

 have a peculiar, spider-like appearance, which is heightened 

 by the habit they have of throwing their legs up over their 

 back when at rest. But two or three species are known from 

 North America, and they are rare. I have never seen them. 



TABLE OF GENERA. 

 1. Metatarsi elontrate. . . . . . NYCTEHIBIA Westwood. 



Metatarsi short. . . ...','.. MECUSTOPODA Macquart. 



