LICE. 159 



vided with lateral scales, but is furnished with an elongated 

 fiu-cate process, which is laid under the belly when at rest. 



These insects are found upon trees and plants, or under 

 stones, whilst some of small size may be met with upon the 

 siu*face of standing water. 



ORDER IV. — ANOPLURA [Parasita Latreille). 



This order is distinguished by having only six legs, by the 

 apterous state of the depressed body, which is not furnished 

 with any lateral or terminal appendages. Their eyes consist 

 of two or four simple ocelli. The order consists of the single 

 genus Pediculus of Linnaeus, comprising the families Pedicu- 

 lid(B and Nermidce. Some recent German authors have, how- 

 ever, considered these two groups as belonging to different 

 orders, placing the Pediculidce amongst the haustellated 

 insects {Hemiptera ejnzoica Nitzsch), and the Nirmidce 

 amongst the mandibulata {Orthoptera epizoica, &c.). We 

 prefer, however, retaining these insects in a single order 

 (Anoplura), on account of their general similarity in struc- 

 tm-e, as well as in their parasitic habits. 



1. The Pediculidce have the mouth minute, tubular, and 

 placed at the anterior extremity of the head, on the under- 

 side, in form of a small rostrum, and inclosing an instrument 

 for suction; the tarsi are composed of a single joint nearly 

 as long as the tibia, and terminated by a single claw of con- 

 siderable size, folding back upon the inside of the tibia, per- 

 forming the office of a hook. 



These insects, which are known under the name of hce, are 

 parasitic upon man and various animals. Of these the Pediculus 

 humanus, or body louse, is of a whitish colour, and almost destitute 

 of markings. This species is very abundant in various parts of 

 Europe, although rare in this country. It frequents the garments 

 and bodies of persons of dirty habits, being exceedingly abundant 

 on the lowest classes in Poland and Russia, Portugal and Spain. 

 The species which is the most abundant in this country is the 

 Pediculus cervicalis, or head louse, which is marked on each side 



