THE yULUS TERRESTRIS. 423 



especially along the ventral surface. It was less able to move 

 than before, the period of throwing off the skin being fast ap- 

 proaching ; the double legs of the sixth and seventh segments, 

 enclosed in their proper skin, were now more elongated, and very 

 much enlarged ; and the new segments were further developed, 

 and the germinal membrane also. Up to this period the young 

 JhIhs is still essentially in an embryonic condition, and it does 

 not acquire the peculiarities of a true larva until the approaching 

 change of skin. This took place by the twenty-sixth day, and 

 the Myriapod was found to have seven pairs of legs and fifteen 

 segments to its body. The antennee had become elongated by 

 at least one-third of their original length, and exhibited at least 

 six distinct joints. The eye still consisted of a single ocellus, but 

 this was now surrounded by a darker-coloured portion of the tegu- 

 ment. The new legs were equal in size and length to the original 

 ones, and were evidently more feeble. The transverse markings on 

 the seven anterior segments were very distinct, and the large brown 

 patch on the seventh ring was darker in colour (Figs. 7 and 8). 

 The whole body was considerably elongated, and this was pro- 

 duced chiefly by the extension of the new segments formed by the 

 germinal membrane. The penultimate and the anal segments, of 

 course, had undergone no change, and they never possess legs. 



By the forty-fifth day more segments were added, and the 

 Juhis began to be torpid, and lay coiled up in a spiral form. 

 The tegument of the body began to assume a whitish, crustaceous 

 appearance, and the animals secreted themselves beneath any dry 

 covering, but avoided parts which were too wet. The principal 

 changes in their general appearance were in the eyes, each ocellus 

 being much more distinct, and in the germinal space, which was de- 

 veloped to its greatest extent ; the six new segments were defined. 



The change of skin is effected in the following manner : — 

 The young Jzihis, when about to cast its integument, bends its 

 body in a semicircular form, with its head inflected against the 

 under surface of the second segment. In this condition it remains 

 for several hours, with its legs widely separated and the dorsal 

 (back) surface of the segments extended. The head is then 

 bent more forcibly on the chest, and a longitudinal fissure takes 

 place on the top of the head, and extends outwards behind 



