358 INSECTA. 



resemble little heaps of gunpowder. We divide them into PODURA and 

 SMTNTHURUS, Lat. 



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 movable 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 membranous and 

 approximated lips with two hooked mandibles. According to Lin- 

 naeus, they form but one genus, that of 



PEDICULUS, Lin. 



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

 ven 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 al- 

 ways 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. 



