334 INSKCTA. 



FAMILY I. 

 CHILOGNATHA. 



THE body generally crustaceous and frequently cylindrical; the antennae 

 somewhat thicker near the end or nearly equal, and composed of seven joints ; 

 the two thick mandibles without palpi, very distinctly divided into two 

 portions by a median articulation with imbricated teeth, implanted in a cavity 

 of its superior extremity ; a species of lip ligula situated immediately above, 

 that covers them, is crustaceous, plane, and divided on its exterior surface by 

 longitudinal sutures and emarginations into four principal arese, tuberculated 

 on their superior margin, the two intermediate of which, narrower and shorter, 

 are placed at the superior extremity of another area, serving as a common base: 

 the feet very short, and always terminated by a single hook. 



The Chilognatha move very slowly, or slide along, as it were, and roll them- 

 selves spirally or into a ball. The first segment of the body, and in some the 

 following one, is the largest, and has the form of a corselet or little shield. It 

 is only at the fourth, in some, and at the fifth or sixth in others, that the 

 duplication of the feet commences ; the first two or four feet are even entirely 

 free to their origin, where they merely adhere to their respective segments by 

 a median or sternal line. The last two or three rings are without feet. A 

 series of pores are observed on each side of the body, which were considered as 

 stigmata, but, according to Savi, they are simply designed to afford a passage 

 to an acid fluid of an extremely disagreeable odour, which appears to serve as 

 a means of defence; the respiratory apertures, for whose discovery we are 

 indebted to him, are situated on the sternal part of each segment, and commu- 

 nicate internally with a double series of pneumatic sacs strung together like a 

 rosary, extending along the body, from which proceed tracheal branches that 

 ramify over the other organs. According to an observation of Straus, the sacs 

 or vesicular tracheae are not, as usual, connected with each other by a principal 

 trachea. 



These Insects feed on dead and decomposed animal and vegetable matters : 

 they deposit in the ground a great number of eggs. According to the system 

 of Linnjeus they form but one genus, that of 



IULUS, Linnaeus. 



Some have a crustaceous body without terminal appendages, and antennae- 

 enlarged near the end. 



GLOMERIS, Lalreille. 



Resembling Onisci ; oval, and rolling into a ball ; the body convex above, 

 and concave underneath, with a range of little scales analogous to the lateral 



