VESTITURE. 

 Flies differ much in the nature of their vestiture. 

 Many are nearly or quite bare; others have a thick, 

 woolly covering of closely set, fine hair; while others 

 still are covered abundantly with a long, stout and heavy 

 bristles or macrochsetse. Doubtless the vestiture has an 

 intimate relation with the habits of the mature insect; 

 just what the relations of the different kinds are, is 

 not yet well understood. Osten Sacken has observed that 

 the eremochsetous kinds (that is those diptera in which 

 there is a general absence of bristles, as, for example, 

 the Stratiomyidse, Leptidae and Tabanidse) are, for the 

 most part, holoptic in the male sex, and at the same time 

 are chiefly aerial in habit, flying swiftly and often hov- 

 ering, using the legs only for alighting and resting. On 

 the contrary, the chaetophorous flies (as the Museidae in 

 the wide sense, Phoridse, Dolichopodidae, Asilidae, etc.) 



