168 I^n'EI!TElU!ATE ANIMALS. 



CHAi'TEj; xvri. 



ORDERS OF INSECTS. 



The known mimlier of insects is so enormous, tlieiv f(.irms are so 

 v.ii'ious, and their lialjits ami instincts are not oiil}' so remarkable, 

 lint have been so fully described, that it were hojieless to attempt 

 here to do more than give the liriefest possible outline of the lead- 

 ing characteis which distinguish the different orders. Tlie .student 

 desirous of further infi^rmation on this head nuist have recourse to 

 treatises specially devoted to entomology. 



Section I. Amktabolk; Insects. — Vmi/ii/ rmt pnssinij throufjh- a 

 nirtiiMiirjj/Kixix, (iinl i/ifrriHi/ fniiii till' fdhilt in size (inhj. Pvrfixt 

 iiixfc-t (ir iiiifiifo drxtifiifi' (if iriiKjs ; ri/cs simple, sometimes waitting. 

 Owing to the fact that the adult ametabolic in.sects have no wings, 

 tliey are often grouped together as a common assemblage, under the 

 name of Aptera. 



Order I. Anoe'Luti-v. 



The insects coni])rised in this order are iiarasitic upon man and 

 other animals, and tliey are commonly known as Lice {Feelieulus, 

 tig. 113, A). They aie all very minute in .size, destitute of wings 

 in the adult state, having a mouth formeil for suction, ,and having 

 either two .simple eyes or iicme. 



()ROER 11. M.VM.OPII.VH.V. 



The.se are kiiown .as " Itird-lice," and are .all minute parasites on 

 different birds or (piadrupcds (tig. IK?, T!). They are distinguished 

 fro]ii the tiiic- Lice by m.t li\iug ujkiu the juices of their host, but 

 ii|iiiii llie more delicite and ti'uder ajijiendagcs of the skin. The 

 iniaitli is, ronseijuently, not suctorial, but htted for biting. 



