74 MR. NEWPORT ON THE ANATOMY AND DEVELOPMENT 



rounded the twelfth and thirteenth segments : and the third (c), the deciduation of which 

 I had the good fortune to witness, while examining the larva for other purposes, was in- 

 ternal to, and partly covered by, the second, and was not forced back further on the 

 ventral surface than to the ninth segment, although, like the preceding, it was entirely 

 removed from the dorsal surface. The whole thus formed a kind of treble sheathing to 

 the posterior segments of the body, until the period when the larva, full-grown to reple- 

 tion, was to prepare for its transformation, become detached from its shell, and leave its 

 deciduated coverings in connexion with it. On the tenth day, October 5th, the larvae 

 had further increased in size, were more raised from the body of the caterpillar, and lay 

 coiled up in a more circular form. Each one was still attached to its egg-shell, although 

 now more than twenty times its size, and each adhered to the caterpillar by its oral 

 organs, exhausting and impoverishing it of its juices. The skin of the parasite again 

 appeared tense and dull, as when about to be cast. The head and thorax had a whiter 

 and more fibrous appearance, the stomach was less easily distinguished through the tegu- 

 ment from other viscera, excepting at intervals, and the heart was seen in motion along 

 the dorsal surface, but with little regularity in its contractions. Its movements appeared 

 to be greatly influenced by the motions of the digestive apparatus, which seemed to induce 

 the tissues around it to contract, and thus excite a reflected action in the circulatory organ, 

 the movements of which appeared to be greatest in the middle of its chambers. The tissue 

 which has hitherto usually been regarded as the adipose — and which I may hereafter have 

 occasion to notice more particularly — was now much extended and augmented in size, and 

 the respiratory organs, although extremely simple, were become well marked. On the 

 eleventh day the larva was still larger, and became detached from the egg-shell; but 

 whether this resulted from accident, or from the completion of its growth, I was not then 

 able to determine. Its tegument had become more opake, and there were tubercular pro- 

 jections at the sides of its abdominal segments, immediately below the line of longitudinal 

 tracheal vessels. On the twelfth day I found that the separation of the specimen from its 

 shell was accidental and premature, and that the larva was unable to re-affix its oral 

 organs to the skin of the caterpillar and perished. This is usually the case when a larva 

 is prematurely detached ; and this result explains the necessity for the continuance of its 

 connexion with the egg-shell, which, as DeGeer has observed of the eggs of Ophion, is so 

 firmly inserted into the caterpillar that it cannot be removed without lacerating the skin. 

 My further observations were now continued on the other specimens of the same brood, 

 which had been more slow of growth. On the fifteenth day one of these was mature, and 

 separated from the shell, leaving its cast teguments forced into a little mass attached to 

 it. DeGeer* formerly noticed that the larva of Ophion left something connected with the 

 egg-shell, but he does not appear to have been aware that it was the entire cast skin of 

 the larva. My specimen of Paniscus now measured somewhat more than half an inch in 

 length, was of a curved form, and was smallest at each extremity. Mr. Westwood f has 

 already indicated this as the general form of body of the larva of this tribe of parasites, 

 and has mentioned that they have lateral fleshy tubercles. He has described the parts of 

 the mouth as consisting of " two obliquely deflexed horny mandibles, very small, slender, 



* Mt'moires. t Introduct. vol. ii. p. 147. 



