sept. 1897] Packard: Transformations of Hymenoptera. Ill 
The legs are very short compared with those of Bombus, only the last pair 
meeting, the terminal joints of the tarsi folded together and lying con¬ 
tiguous to each other; tarsi much shorter and thicker than in Bombus. 
Abdomen broader and squarer, more truncated at tip than in Bom¬ 
bus, the terminal urites as in Bombus ; the rhabdites nearly retracted, 
iorming a pair of papillae which are rounded and thick. 
The body is less curved on itself and the prothorax shorter. The 
mesoscutellum is less prominent and convex, while the abdomen is 
longer and narrower; the segments more thickened at the end, and 
spined more prominently. 
The tegulae are, as in Bombus , divided into an anterior flattened area, 
on the side of which, just above the pleurites, are the spiracles, and a 
posterior raised thickened area on the posterior half of the segment, 
which is much flatter, less ridged and convex than in Andrena, resem¬ 
bling Bombus more in this respect; this flattened ridge widens more 
towards the pleurites. The pleural region with elevated thickened tub¬ 
ercles, a separate knob on each segment. The ridges on the tergites 
and pleurites are no more distinctly marked on the prothorax than 
elsewhere, and not, in fact, so much as on the abdomen. Beneath 
the sternites are a little more ridged, more convex than in Andrena. 
The whole surface above and beneath is covered with minute hairs, 
which are absent in A?idre?ia. 
The pupa can at once be distinguished from that of Andrena by the 
prothoracic segment not being thickened any more and not quite so 
much as the abdominal ones, by the head being a little larger, and by 
the body not so rapidly tapering towards the head, and being thickest 
on the posterior one-fifth. 
In all these characters Megachile closely approaches Bombus. In the 
head-characters it closely resembles Bombus ; the clypeus, however, is 
not so small and distinct, and the labrum is a little larger, and less dis¬ 
tinctly bilobate, while also the supraclypeal area is quite different, not 
being so triangularly depressed ; posteriorly the shape is much the same. 
The labrum differs in the tips being rounded, fleshy, and with a termi¬ 
nal lunate area. The maxillae are more acute, terminating in longer 
spines. The body is broader and flatter, the pleural region a little more 
prominent, and the terminal segment quite different, the tergite being 
much smaller than the sternite, which is very different from that of 
Botnbus. Megachile does not have the minute thoracic tubercles end¬ 
ing in minute spines present in Bombus; the thickenings of the rings 
posteriorly are more marked in Megachile than in Bombus , and the 
body is more hirsute. 
