88 Mr. A. S. Packard on the Development 



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 sepa- 

 rated into the two lateral halves, being transversely narrow tri- 

 angular 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 mesoscutellum. 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. Whereas before it was a segment much narrower 

 than those contiguous, it has now become still smaller, and its 

 tergal portion, instead of being nearly horizontal, is now much 

 inclined downwards posteriorly. 



The abdomen, though still larger, approaches much nearer 

 the form of the pupal abdomen than before, and the segments 

 are flatter. The second ring has become much contracted, as it 

 is destined to become the " pedicel " or " first abdominal seg- 

 ment" of descriptive entomology. There is now a differentiation 

 of the elements of the ring. Thus the tergites (notum, fig. 3/) 

 are clearly distinguished from the pleurites (fig. 3 e, flanks) and 

 urites (Lacaze-Duthiers, fig. 3 d, ventral side). The spiracles are 

 situated on the upper edge of the pleurites, opening out just 

 under the edge of the tergite. As we go back towards the tip 

 of the abdomen, the tergites as well as the urites decrease in 

 width, while the pleural region or pleurites increase in size. It 

 is the pleural portion, however, which is afterwards to become 

 absorbed, by which the dorsal and ventral portions of the abdo- 

 men approximate more intimately and overlap each other, thus 

 making the tip acute, as in the pupa (fig. 4) and especially the 

 perfect bee. 



During this time the ovipositor, owing to the diminished size, 

 by absorption, of the parts supporting it, has become gradually 

 more and more retracted, while the entire tip of the abdomen is 

 more acute and incurved. 



The Pupa State. 



In this stage (fig. 4) the whole body is shorter, and there is a 

 decided transfer of the bulk of the body towards the head. The 

 head has increased in size, the thorax is one-third larger, while 

 the greatly shortened abdomen is a third shorter than in the 

 preceding stage. At this period the longitudinal axis of the 

 body is less curved than before. The mesoscutellum is now 

 placed just in the middle of the body, when before it was situ- 

 ated at the anterior third. This change also carries the wings 



