INSECTA. 359 



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, besides, undergo true meta- 

 morphoses, analogous to those of several Diptera, such as the 

 Tipulas. 



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 dis- 

 cover a little movable body furnished with small spines. The legs are 

 strong, the last ones particularly, fitted for leaping, and spinous; the coxa 

 and femur are large; the tarsi is composed of five joints, the last terminating 

 in two elongated hooks; the two anterior legs are inserted almost under 

 the head, the rostrum being placed midway between them. 



The female lays a dozen of white and slightly viscid eggs; the larvx 

 have no feet, are much elongated, resemble little worms, and are extremely 

 lively, rolling themselves into a circle or spirally, and crawl with a serpen- 

 tine motion; they are first white and then reddish. Their body is com- 

 posed 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 larvje push themselves forwards. After remaining twelve 

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

 which they become pupse, and from which, in about the same time, they 

 issue in their perfect state. 



There are various species that live on Quadrupeds, Birds, &c. 



