NEEVOUS SYSTEM. 89 



and Coreus tristis. At this period I could not detect 

 any traces of a labium. The feet end in two claws, 

 one being very minute and slender. Neither at this 

 nor in the larval state could any traces of the tracheae 

 be observed, and I doubt whether they exist. 



" The embryo, when about to hatch, throws off the 

 eggshell and ' amnion ' (or ' larva skin') in a few seconds. 

 The larva is perfectly white, and is very active in its 

 movements, running over the damp inner surface of 

 the back. The larva (figs. 15, 15 a, spring; 16, 16 «, 

 under side of the head, showing the mandibles and 

 maxillas, II, III; 17, the same seen ventrally) is a little 

 over one hundreth of an inch in length, and differs from 

 the adult in being shorter and thicker, with the spring 

 very short and stout ; while the head is much rounded, 

 and the antennce are stout and thick. In fact, the 

 larva assumes the form of the lower genera of the 

 family, such as Acliorutes and Li/pura, the adult more 

 closely resembling Degeeria. 



" The larva after moulting retains its early form, 

 and is still white. It is then two and a half hun- 

 dredths of an inch in length. After a second moult 

 the body becomes purplish, translucent, and in form 

 much mxOre slender, resembling the adult. 



" The eggs are laid and the young are hatched appa- 

 rently within a period of from six to ten days." 



The nervous system of Tomocerus consists of five 

 ganglia, two of which, the supra- and infra-oesophageal, 

 lie in the head, and are connected as usual by short 

 commissures, between which the oesophagus passes. 



Nicolet was unable to discover the nervous system 

 in the linear Collembola, while that of the globular 

 species appeared to me much more difficult to make 

 out. As described by Nicolet Smynthurus has, like 

 Tomocerus, two ganglia in the head and three in the 

 cephalothorax. The linear species have generally two 

 ganglia in the thorax and at least one in the abdomen. 



So far as I am aware, no naturalist had given any 

 account of the muscular system of the Collembola 



