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. 3c) 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 rmg. ‘Thus the tergites (notum, fig. 3 f) 
are clearly distinguished from the pleurites (fig. 3, 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 
