572 Prof. J. 0. Westvvood's MonograpJi of 



This is evidently the sheath of the proboscis. The cases 

 of the two fore legs are very short aud bent back at the 

 extremity of the femora, lying close upon the breast, whilst 

 the cases of tlie two middle legs are more elongated, also 

 resting uj)on the breast and extending as far as the Aving 

 covers; which latter cover the cases of the hind legs, except 

 the extremity of the tibiae and the five-jointed tarsi. The 

 abdomen is very robust and convex, each segment having 

 a strong, short, curved bristle at each side, whilst the dorsal 

 surface of each of the principal segments is furnished with 

 a transverse row of very short, fine spines, which doubtless 

 assist, with the latci^al spines, in enabling the insect to push 

 itself forward through the front orifice of the cocoon when 

 the cap is removed. 



No one looking at this pupa Avould have supposed that 

 it could have produced such an elongated, slender imago 

 as the S 1/ sir opus ; but, fortunately, in one of the specimens 

 the perfect insect had been secured in the act of making 

 its escape fi-om the pupa case, as represented in figure 9. 

 ]\Ioreover, there can be no doubt from the necromor])hous 

 character of the pupa (the limbs lying free, not soldered 

 down as in the pupa of Le])idopterous insects), that the 

 pupa is really that of a Dipterous insect and not of a 

 Lepidoptcrous insect, within which the parasitic Dipteron 

 had been reared. Although searched for with much care 

 I did not succeed in finding, lying ^vitliin the cocoon, any 

 portion of the skin of the larva by which it had been 

 formed, and suppose, therefore, that the parasite had en- 

 tirely devoured it. Hence arises the question as to the 

 precise nature of the parasitism of the Sy sir opus. Was 

 its larva an internal parasite, like the larva of the Ta- 

 cliince ? or was it external, like the larva of Scolia, as 

 described by Passerini ? The latter seems to imply diffi- 

 culties in the formation of a compact, oval cocoon, like 

 that before us, by a caterpillar infested by an external 

 parasite, unless we svippose that it was not until the cocoon 

 had been formed, that the egg of the parasite, which had 

 been attached to the outer surface of the caterpillar, had 

 hatched, so as to enable the parasitic larva to feed without 

 hindrance upon its prey within the closed cell of the cocoon. 

 Further observations are therefore needed to determine this 

 curious question. 



The specimen of the imago making its escape from the 

 pupa skin, as shown in fig. 9, exhibited the different parts 

 of the mouth in a condition very different from their ap- 



