OF CERTAIN CHALCIDIDZ AND ICHNEUMONIDE. 73 
membranes with its shell, although it is completely apodal and incapable of locomotion, 
and has to derive nourishment, not by simple endosmosis through its foetal envelopes into 
the tissues of its body by similar means, but by the direct abstraction of fluid from another 
living body into its own. To ensure this, the larva requires to be attached by its terminal 
segments to its shell during the whole period of its growth, and like the larvæ already 
described, it passes no fæces until it has attained its full growth, and becomes detached 
from its shell, to prepare for its change to a nymph. 
After the second day I was accidentally prevented for some time from making any very 
precise observations on these insects, further than noticing that they grew rapidly from 
day to day, and that they retained their connexion with the shell. 
On the 4th of October, the ninth day of their existence, I was enabled to resume my 
examinations of them, and then found that several of them had perished, and that three 
only remained healthy and thriving. The caterpillar on which they had fed had become 
shrunken and wasted, but still retained sufficient irritability and muscular power to 
contract its body with a quick lateral motion when touched. . The larvæ that remained 
healthy were now at least twelve times their original size (fig. 16). The head (16 a) of 
the larva, which at first was the most ample region of its body, was now the smallest, 
relatively to other parts which had increased. more rapidly, and. but little exceeded the 
size of the ovum. The parasites were attached, one on the dorsal surface and one on each 
‘side of the caterpillar, the latter one coiling round the inferior surface of the thoracic seg- 
ments (fig.17). Their bodies, enlarged and fattened, were of a dark pea-green colour, and 
were formed each of fourteen segments, all of which, more especially the anterior ones, 
were distinctly marked. The stomach in each was in a state of incessant to and fro ver- 
micular motion, and had become enveloped in a thick tissue of little white follicles, which 
have been regarded as the rudiments of fat-vesieles. No anal outlet had yet been formed, 
nor was there, so far as I could discover, any perforated intestine. In the interval of 
i hich I had been prevented from following up my observations, each 
nz i T believe, is the first time that the soft- 
larva had three times cast its tegument. This, | 
bodied Hymenopterous larvæ have been noticed to undergo this change. These larvæ, 
therefore, as I have already pointed out, are not exceptions, as they have been suspected 
to be, to the general rule of development in hexapods, in so far as refers to the casting of 
the skin; although, as the body is still connected with the egg-shell, the ^l ee 
are not entirely got rid of until the larva is detached to become a nymph. Ihe skin 1s 
fissured in Paniscus, as in other larvæ, along the dorsal surface of the anterior thoracic 
segments, and is gradually removed from the dorsal, lateral, and inferior — of 4 
head and succeeding segments, by the growth and expansion of the er =~ 
itt angen nrg el d 
wards, as much by the rapidity of growth in the parts beneat „as by the » " 
muscular contractions of the segments. When I re-examined my specimens on the mm 
oved further than to the posterior segments of 
: m 
day, neither of the cast layers had been gode shed skin (fig. 16 a) was attached to the 
the body, which they partially inclosed. surrounded by the shell, and covering the inferior 
anal segment, and enveloped this part, dein 
ithi st, but larger and more corrugated, p y sur- 
surface. The second (6), within the fir g à 
VOL. XXI. 
