32f> SYSTEMATIC ARRANGEMENT 



it is obvious that the number necessary to do this 

 must be astonishingly great. About 1700 have been 

 named as belonging to this country ; and it is pro- 

 bable that they will ultimately be found not to fall 

 short of 2000. 



Allusion has been already made to the injuries 

 they commit, in the larva slate, both to our domestic 

 animals and to agricultural produce ; but the pur- 

 poses to which they are subservient in the economy 

 of nature, are highly important and beneficial. Many 

 of the smaller birds, as well as some other of the 

 higher animals, depend upon them almost exclusively 

 for food, and they are the most efficient instruments 

 employed by nature in removing both animal and 

 vegetable substances when rendered offensive and 

 unwholesome to other animals by decomposition. 



The most successful of the more recent investi- 

 gators of this order are German and French Ento- 

 mologists, particularly Meigen, Fallen, Wiedeman, 

 Macquart, and Robineau Desvoidy. The following 

 is Macquart's arrangement, slightly modified, for 

 which we are indebted to Mr. Westwood's useful 

 text-book:* 



SECTION I. (Ovipara or Larvipora ; DIPTERA, Leach.) Head 

 distinct from the thorax ; sucker enclosed in a labial canal ; 

 claws of the tarsi simple, or with one tooth ; the transfor- 

 mation to the pupa state not taking place within the body 

 of the parent. 



Division I. (NEMOCERA.) Antennae having six or more 

 distinct joints ; palpi with four or five joints. 



* Page 420. 



