332 



the labium (fused montum and submentum) is almost square 

 in shape, and from it spring the medium-sized labial palps. 

 The distal portion of the labium (fused endopodites) is slightly 

 wider than the proximal portion (fig. 14), and its surface 

 is developing a very delicate pubescence. The labial palps 

 are rather club-shaped, with a distinct indication of three 

 segments ; bristles are already clearly visible on them. The 

 first maxillae have shrunk to rather short, stylet-like struc- 

 tures (fig. 14), and have developed bristles; while the huge 

 maxillary palps of the early pupa have shrunk to a pair of 

 graceful, four-jointed appendages, on which bristles have also 

 begun to develop. 



The shrinking of the mandibles has been less pro- 

 nounced; each has assumed the shape of a powerful, slightly 

 curved jaw, armed distally with three (occasionally with four) 

 short blunt teeth; the mandibular palp has entirely dis- 

 appeared and its position is indicated, now, only by the 

 chitinous tubercle of the pupal sheath. 



The labrum does not undergo any marked changes, except 

 a diminution in size. 



As a result of these processes the mouth appendages, in 

 the shapes in which we see them in the adult, have been 

 produced; chitinisation of this cellular mould, which soon 

 ensues, results in the more marked segmentation and the 

 hard consistency of the mouth parts, such as we see them in 

 the mature wasp. 



The antennae, meanwhile, have been undergoing changes 

 parallel to these; at the time of pupation, as we saw, the 

 antennae were in the form of two thick, slightly segmented 

 appendages lying laterally along the ventral side of the 

 thorax. 



In the early pupal periods the segmentation becomes 

 more distinct, and at the same time shrinking takes place; 

 as a result of these processes, the antennae adopt their adult 

 appearance after about thirty-six hours ; bristles, which are 

 first seen some eight hours after pupation, are well marked 

 at this stage ; rapid chitinisation of the surface of the antennae 

 ensues, resulting eventually in the production of the fully 

 developed appendages. 



The antennae of the male and female differ slightly ; in 

 both sexes there is a long proximal joint, followed bv a 

 joint about one-third the length of the first; then come two 

 very small joints, followed by nine larger ones, all of about 

 the same size. In the female the last three joints are arranged 

 so as to form a very distinct club (fig. 11); in the male no 

 such modification can be seen. 



The chief point of interest in the dev-elopment of the 

 mouth appendages is the occurrence of a mandibular palp, 



