INTRODUCTION. 



XXV 



crystallized into a permanent shape ; second, because nearly 

 all the existing literature has the nomenclature here employed 

 and to use a new one would largely defeat the object of the 

 work in the liands of the beginner. I give below the ter- 

 minology used by Comstock, together with the equivalent 

 terms here used and the equivalent ones in the terminology 

 of Schiner, for the horse-fly. 



Flies differ very much in the nature of their covering. 

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

 covering of closely set, long fine liair ; while others still have 

 an abundant covering of long stout, heavy bristles or macro- 

 cliwta'. Undoul)tedly the kind of covering has much relation 



