INSECTA. 



125 



Genus II. Ricinus, Beg. 



Mouth composed externally of two lips and two mandibles, 

 resembling hooks ; tarsi articulated and terminated by two 

 equal hooks. All, with the exception of the Dog species, live 

 upon Birds. 



FAMILY III. SUCTORIA. 



Instead of a mouth a sucker of three pieces, included be- 

 tween two laminae, forming, together, a trunk or beak, either 

 cylindrical or conical. Only one genus. 



Pulex, Lin. Flea. 



Body oval, compressed, clothed with a sufficiently firm 

 skin, and divided into twelve segments. Head small, with a 

 little round eye on each side. Feet strong, particularly the 

 hind ones, which are the longest, and enable these animals to 

 leap more than two hundred times their own height. Fleas 

 are not born under the form in which we recognize them ; 

 their eggs produce little larvse, without feet, and like worms ; 

 they are exceedingly lively, rolling themselves into a circle, 

 or spirally, and crawling with a serpentine motion ; they are 

 at first white, and then reddish. After remaining for twelve 

 days in this shape, they enclose themselves in a little silky 

 cocoon, where they become nymphs, and whence they issue 

 in the perfect state at the expiration of twelve days again. A 

 particular species, known in America bv the name of chigre, 

 introduces itself under the nails of the feet and hands, and 

 beneath the skin of the heel, and there soon acquires the vo- 

 lume of a small pea, by the rapid growth of the eggs which it 

 carries in a membranous sac beneath the abdomen. 



ORDER IT. COLEOPTERA. 



Four wings, of which the superior, called elytra, are gene- 

 rally hard, thick and short, serving as cases for the inferior, 

 which are membranous, and folded transversely; head pro- 

 vided with two antennse, of various forms, and almost always 



