SUCTORIA. 263 



This order consists of a single genus, that of 



PuLEx, Lin, 



The body of the Flea is oval, compressed, invested by a firm skin, 

 and divided into twelve segments, three of which compose the trunk, 

 that is short, and the others the abdomen. The head is small, strongly 

 compressed, rounded above, and truncated and ciliated before; it is 

 furnished on each side with a small rounded eye, behind which is a 

 fossula, in which we discover a little movable body furnished with 

 small spines. At the anterior margin, near the origin of the ros- 

 trum, are inserted the pieces considered as the antennae; they are 

 scarcely the length of the head, and are composed of four almost 

 cylindrical joints. The sheath or rostrum is divided into three seg- 

 ments. The abdomen is very large, each of its annuli being divided 

 into or forming two laminae, one superior and the other inferior. The 

 legs are strong, the last ones particularly, fitted for leaping, spinous, 

 the coxa and femur large, the tarsi composed of five joints, the last 

 terminating in two elongated hooks; the two anterior legs are in- 

 serted almost under the head, the rostrum being placed midway be- 

 tween them. 



The male, in coitu, is placed under the female, so that they face 

 each other. The latter lays a dozen of white and slightly viscid 

 eggs: the larvae have no feet, are much elongated, resemble little 

 worms, and are extremely lively, rolling themselves into a circle or 

 spirally, and crawl with a serpentine motion; they are first white 

 and then reddish. Their body is composed of a scaly head, without 

 eyes, bearing two very small antennae, and of thirteen segments, 

 with little tufts of hairs, the last one terminated by two kinds of 

 hooks. Some small movable pieces are observed in the mouth, by 

 which these larvae push themselves forwards. After remaining 

 twelve days under this form, they enclose themselves in a little silky 

 cocoon in which they become pupae, and from which, in about the 

 same time, they issue in their perfect state. 



Pulex irritans, L.; Roes., Insect., II, ii, iv. The common 

 Flea feeds on the blood of Man, the Dog, Cat, bzc; the larvae 

 live in the dirt that is collected under the nails of filthy indi- 

 viduals of the human family, in the nests of Birds, particularly 

 of Pigeons, where they fasten to the neck of their young, and 

 suck their blood to such a degree as to become perfectly red. 

 Pul. penetrans, h.; Catesb., Carol. Ill, x, 3(1). This species, 



(1) M. Dumeril has given an excellent figure of this animal in his work, Con- 

 sid. Gen. sur la Classe des Tosectes, and in the Diet, des Sc. Naturelles. 



