M1RUPODA. 34? 



FAMILY I. 



CHILOGNATHA*. 



The body generally crustaceous and frequently cylindrical; the 

 antennae somewhat thicker near the end or nearly equal, and com- 

 posed of seven joints ; two thick mandibles without palpi, very dis- 

 tinctly divided into two portions by a median articulation with imbri- 

 cated teeth, implanted in a cavity of its superior extremity; a species 

 of lip ligulaf situated immediately above, that covers them, is 

 crustaceous, plane, and divided on its exterior surface by longitudinal 

 sutures and emarginations, into four principal areae, tuberculated on 

 the superior margin, the two intermediate of which, narrower and 

 shorter, are placed at the superior extremity of another areae, serving 

 as a common base : the feet very short, and always terminated by a 

 single hook ; four feet, situated immediately under the preceding 

 part, of the form of the following ones, but more closely approxi- 

 mated at base, with the radical joint proportionably longer ; most of 

 the other attached in double pairs to a single annulus. The male or- 

 gans of generation are situated immediately after the seventh pair of 

 feet, and those of the female behind the second. The stigmata are 

 placed alternately, outside of the origin of each pair of feet, and are 

 very small. 



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

 roll themselves 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 is 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 aper- 

 tures, for whose discovery we are indebted to him, are situated on 



* CIIILOGXATA, Lat. or the genus IULUS, Lin. 



f The lower lip composed of the two pairs of jaws of the Crustacea, according 

 to Savigny. 



