44 



NORTH AMERICAN DIPTRRA. 



are for the most part ambulatory insects, using their legs 

 as much as, sometimes more than the wings in locomo- 

 tion ; or, if not, for grasping, seizing or holding their 

 prey; they seldom have the eyes contiguous in the male 

 sex. Probably the macrochsetse reach their highest de- 

 velopment among the Tachinidae, as for instance in 



Fig. 21. Paradejeania, sp. (Brazil). Enlarged. 



Dejeania, Paradejeania, etc., and the Dexiidae (Hys- 

 trichodexia}, where the abdomen may be almost covered 

 with long, erect, very rigid spines. 



As concerns other kinds of vestiture, the usage of 

 writers is not very exact; the terms hair, pile, pubes- 

 cence, tomentum, being used with a wide degree of lati- 

 tude. In general, however, pile should be restricted to 

 indicate closely and thickly set, erect, fine hair like the 

 pile of velvet; while the term hair may be used to desig- 

 nate longer, less erect, and less abundant pelage. Pu- 



