ORDER CHILOGNATHA. 151 



ORDER I. CHILOGNATHA (Latreille). 



Body long, cylindrical; antennae 7-jointed; two strong 

 mandibles, articulated in the middle, destitute of palpi ; legs 

 very numerous. 



ORDER ii. CHILOPODA (Latreille). 



Body long, depressed ; antennae, at least 14-jointed; man- 

 dibles furnished with a palpiform appendage ; legs very nu- 

 merous. 



ORDER III. THYSANURA (Leach). 



Body of moderate length; legs six; abdomen furnished 

 at the sides with moveable pieces, or terminated by appen- 

 dages for leaping. 



ORDER IV. ANOPLURA (Leach). 



Body of moderate length ; legs six ; abdomen not fur- 

 nished with lateral or anal appendages. 



ORDER i. CHILOGNATHA (Latreille, MacLeay). 

 This order, corresponding with the apterous genus lulus 

 of Linnaeus, is distinguished by having the body long, crus- 

 taceous, and often cylindric, and the antennae 7-jointed : 

 they are possessed of a very great number of legs ; the 

 abdominal are not distinguished from the thoracic seg- 

 ments : the antennae are two in number ; the eyes are 

 composed of an union of ocelli, and if, in some species, 

 these organs offer a facetted cornea, each of the lenses 

 is much larger and more distinct than in the true reticu- 

 lated eyes of insects ; the number of the legs, as well as 

 of the segments of the body, increases with the age of the 

 animal. These animals live, and continue to increase in 

 size, for a much greater period of time than insects ; and, 

 according to M. Savi, two years are required before the or- 

 gans of generation become at all apparent. Hence we may- 

 conclude, that they approach, in some respects, to the Crus- 

 tacea and Arachnida, and in others to the true insects ; but, 



