152 AMETABOLA. 



from the consideration of the presence, the form, and the 

 direction of the tracheae, they must be considered rather as 

 related to the latter. The legs are very short, terminated by 

 a single claw ; two short antennae ; the mandibles are crusta- 

 ceous, without palpi, and 3-jointed ; but the more distinguish- 

 ing character of the Chilognatha is the position of the sex- 

 ual organs near the anterior part, and not the extremity of 

 the body ; those of the male being placed behind the seventh 

 pair of legs, and those of the female behind those of the se- 

 cond pair. These animals walk but slowly, and with an un- 

 dulating motion, produced by the progressive action of the 

 numerous legs ; the majority of them, when disturbed, roll 

 themselves up into a ball. They feed upon animal and vege- 

 table substances in a state of decay, and lay a very consider- 

 able number of eggs in the earth. From these eggs the 

 young are produced, at first without any appendages to the 

 body ; eighteen days afterwards, however (in the genus lulus, 

 according to M. Savi of Bologna, who has made these insects 

 the subjects of two valuable memoirs), the skin is cast, when 

 they appear with twenty-two segments, and twenty-six pairs 

 of legs, of which, the first eighteen serve for locomotion ; at 

 the second moulting the animal has acquired thirty-six legs, 

 and at the third forty-three, the body being then composed 

 of thirty segments ; and in the adult state, the male has thirty- 

 nine, and the female sixty-four. 



A very small species of this group attacks the strawberry, 

 another the endive ; others are found in moist places, under 

 the bark of trees, &c. 



There are numerous species belonging to this order, some 

 of those from South America acquiring a large size the 

 In I us nun-! tun* being seven inches long. Of the British spe- 

 cies, Dr. Leach has given a very good monograph in tin- 

 Zoological Miscellany. 



This order is divided by Latreillc, in Ins last work, into 

 three families: 



