86 MR. NEWPORT ON THE ANATOMY AND DEVELOPMENT 



supported by the fact that I have never yet met with even the youngest larvae between the 

 skin and muscles of the caterpillar, but always internal to the muscles, imbedded in the 

 so-called fatty tissue, between them and the alimentary canal, and always on the dorsal 

 surface, and usually with its head in the direction of that of the caterpillar. I have found 

 it in different stages of growth, from one-fourth to three-eighths of an inch in length (a), 

 as early as the middle of August, when it is of a light pea-green colour; but I have obtained 

 full-grown specimens (c, d) only from the pupa of the Sphinx, sometimes as early as the 

 end of October, but more frequently not until the commencement of March, and sometimes 

 as late as the end of April. Usually, one egg only is deposited in each caterpillar, but 

 sometimes there are two, and both become hatched, although of the parasites one only 

 arrives at maturity, as one is invariably destroyed by the other. I have the following 

 entry of a fact of this kind in my note-book with the date " March 13, 1832," which shows 

 that two larvae may exist in the pupa of the Sphinx up to a late period, but that one is 

 then destroyed. " The pupa now examined was one in which Ichneumon Atropos had 

 deposited two eggs. Two larvae had been hatched, and these were located in the lower 

 part of the abdomen of the pupa. One of them was very small, being scarcely more than 

 one-fourth of an inch in length, and appeared to have been dead for some time. The 

 other was a fat well-fed specimen, about three-quarters of an inch in length and one-sixth 

 in diameter. It seemed to have destroyed part of the fatty sacculi of the Sphinx, and 

 was lying in the cavity of the body, but it had not injured the upper part of the digestive 

 apparatus, the stomach, behind which it lay so imbedded that I had almost mistaken it at 

 first for the intestine and colon, which had not undergone their proper change. The 

 nervous system of the pupa had not been injured by the larvae, although its changes had 

 been retarded. It thus appears that the Ichneumon sometimes deposits more than one 

 egg in the body of the caterpillar, as several times before this I have found two of these 

 larvae in the same insect, although, I beHeve, never more than one of them comes to 

 perfection." All my subsequent observations have confirmed this conclusion. 



The usual situation of the parasite in the Sphinx-pupa is in the tissue of the middle 

 part of the body beneath the dorsal vessel and above the stomach, on which it often rests. 

 This is the position of the full-fed larva in the drawing and preparation (fig. 3), and this 

 is the specimen alluded to and partly described in my second memoir on Meloe, printed 

 in the Society's Transactions, vol. xx. p. 335. It was obtained at almost the latest period 

 of the larva state, on the 18th of April, 1832. The other specimens exhibited were pro- 

 cured between that period and the month of October, so that the insect continues to sub- 

 sist on the Sphinx, and probably passes into a state of hybernation with it, during the 

 long interval of six months. One specimen found on the 20th of March, and removed 

 from the body of the pupa into water, lived several days, while another, not placed in 

 water, spun a few delicate threads to prepare for its change to a nymph. This change 

 usually takes place in April, but when placed in water at that period it soon perishes, as 

 its respiration has then become more active, as the following entry from my note-book 

 shows : — " April 21, 1832. On dissecting a male pupa of Sphinx ligustri, a few days ago, 

 I found, somewhat to my mortification, one of my old friends, the larva of Ichneumon. It 

 was a large and full-fed specimen, and laid with its anterior portion in the thorax, and its 



