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, 

 forming a pair of papilla; 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 thiclcened at the end, and 

 spined more prominently. 



The tegulje 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 Andrena. 



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 diff"erent, not 

 being so triangularly depressed ; posteriorly the shape is much the same. 

 The labrum difi'ers in the tips being rounded, fleshy, and with a termi- 

 nal lunate area. The maxillEC 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 diff"erent, the tergite being 

 much smaller than the sternite, which is very diff^erent from that of 

 Bombus. 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 Bombics, and the 

 body is more hirsute. 



