;;{.s INSECTA. 



ORDER III. 



PARASITA. 



THE Parasita, so called from their parasitical habits, have but six legs, 

 and are apterous, like the Thysanoura; but their abdomen is 

 destitute of articulated and moveable appendages. Their organs 

 of vision consist of but four or two ocelli ; a great portion of 

 their mouth is internal, exhibiting externally either a snout or 

 projecting mammilla, containing a retractile sucker, or two mem- 

 branous and approximated lips with two hooked mandibles. According to 

 Linnaeus, they form but one genus, that of . 



PEDICUJLUS, Linnceus. 



Their body is flattened, nearly diaphanous, and divided into twelve or 

 eleven distinct segments, three of which belong to the trunk, each bearing one 

 pair of legs. The first of these segments frequently forms a sort of thorax. 

 The stigmata are very distinct. The antennae are short, equal, composed of 

 five joints, and frequently inserted in a notch. There are one or two small 

 ocelli on each side of the head. The legs are short, and terminated by a very 

 stout nail, or two opposing hooks, which enable these animals to cling with 

 great facility to the hairs of quadrupeds, or to the feathers of birds, whose 

 blood they suck, and on whose bodies they pass their lives. They attach their 

 ova to these cutaneous appendages. These insects always live on the same 

 quadrupeds and on the same birds, or at least on animals of these classes, 

 which have analogous characters and habits. Two species frequently live on 

 the same bird. Their gait in general is very slow. 



This genus now forms several subgenera. They include the various species 

 of lice found on man, birds, &c. 



ORDER IV. 



SUCTORIA. 



THE Suctoria, which constitute the last order of the Aptera, have a mouth 

 composed of three pieces, enclosed between two articu- 

 lated laminae, which, when united, form a cylindrical 

 or conical proboscis or rostrum, the base of which is 

 covered by two scales. These characters exclusively 

 distinguish this order from all others, and even from 

 that of the Hemiptera, to which, in these respects, it approximates the most 

 closely, and in which these insects were placed by Fabricius. The Suctoria, 



