Packard.] 284 



to assume a spherical form, while the elongated abdomen is shortened 

 and very perceptibly altered in form, apj^roaching near that of the 

 pupa, while the whole body is flexed more upon itself. 



The head is still closely appressed to the prothorax, but much less 

 so than formerly, since the increasing size and different proportions of 

 the prothorax have pushed it away. This act of separation has 

 effected an important change in the position of the head as related 

 to that of the rest of the body. It is now truly vertical. Before, its 

 greater length was more continuous with the longitudinal axis of the 

 body, that is, nearly horizontal, or rather inclined at a slight angle 

 fi'om the longer axis. The horizontal position is normal in the low- 

 est insects, as the neuroptera. In the hymenoptera, the longer axis 

 of the head is most completely vertical. 



The head in its size, and the development of the appendages, includ- 

 ing the mouth-parts, now begins to resemble those parts in the pupa. 

 The eyes are larger and more distinct than before, the maxillse and 

 antenna3, though still very short, are shaped more like those parts in 

 the pupa. In the antennge, the most marked change takes place in 

 the three basal joints, or the "scape," of which the second joint now 

 becomes the longest and somewhat contracted in the middle, and 

 round at the extremity ; while the terminal joints are still doubled 

 upon themselves, and rest folded upon the mouth-parts. 



The thorax also resembles that of the pupa, though longer, and the 

 basal ring of the abdomen (propodeum) is still exposed to view when 

 seen from above. At this stage the prasscutum of the mesotho- 

 rax, before very distinct, is no longer seen, as in the pupa it is mostly 

 absorbed, and passes out of sight, though in the Tenthredinidae it is a 

 large and conspicuous portion of the mesonotum. 



Most interesting changes have occurred in the hinder part of the 

 thorax. Where in the previous stage the meso-scutellum was immersed 

 in the ring to which it belongs, it is now elevated, and become very 

 prominent, the thorax posteriorly falls rapidly away from it at an 

 angle of about 60°, and its hinder edge is much thickened and folded 

 down on itself. The metathorax is entirely visible from above. The 

 scutum is now entirely separated into the two lateral halves, being 

 transversely narrow, triangular pieces, the bases of which are square 

 and closely adjoin the insertion of the hind wings, while their apices 

 are much produced, and extend under the meso-scutellum. The 

 meta-scutellum is now distinctly seen to be a linear transverse piece 

 reaching on each side to the middle of each half of the scutum. The 

 basal ring of the abdomen (propodeum. Fig. 3, c,) is now undergoing 

 the process of being transferred from the abdomen to the thorax. 

 Where before it was a segment much narrower than thpse contiguous, 



