72 W.M. H. ASHMEAD. 



Abdomen above less distinctly convex, somewhat flat, depressed, rarely 

 subconvex ; terminal tarsal joint without a pulvillua between the 

 claws. 



Second cubital cell receiving both recurrent nervines; stigma poorly de- 

 veloped, narrowed, but about twice as long as wide; submedian and 

 median cells most frequently equal, rarely with the submedian the 

 longer; abdomen never banded or maculate with white or yellow, at 

 most with hair bands. Subfamily II. Megacuilin.e. 



Second cubital cell receiving only one recurrent nervine — the first, the 

 second recurrent joining the radius a little beyond the second trans- 

 verse cubitus, or at most interstitial with it ; stigma scarcely devel- 

 oped, at most not or scarcely longer than wide; submedian cell most 

 frequently a little longer than the median], sometimes equal with it ; 

 abdomen above bare, always banded or maculate with yellow-white 

 or rufous, never fasciate with hair hands. 



Subfamily III. Anthidiin.k. 



Subfamily I. Osmund. 



(The Mason Bees). 



The bees placed in this subfamily are readily separated or distin- 

 guished from the next two families, into which I have divided the 

 family, by always having u distinct pulvillus between the c/<iir.<, a 

 character not possessed by the other two subfamilies. They have, 

 too, quite a distinct habitus of their own, scarcely definable, but 

 readily recognizable by the experienced eye, their heads I icing 

 slightly different in shape, with usually broader temples, the abdo- 

 men more convex above and rarely with distinct white hair bands 

 as in the Megachilimo. Their color, as a rule, is different, being 

 more or less metallic, dense black, blue-black or blue, and through 

 blue-green to a bright metallic green and cupreous. 



The species in only a few genera resemble certain Megachilinse, 

 i. e., Trypetes, Heriades, Chilostoma, Ashmeadiefla, etc., and these 

 must he examined with care to distinguish them from some Mega- 

 chi lines. 



The habits of the species in this group, so far as they are known, 

 also support their separation as a distinct group from the others. 

 Their nests are made in old posts, trunks and limbs of old and 

 decaying trees, or in the interstices of stone walls, etc., the par- 

 titions between their cells being filled with clay and sand or other 

 material, the cells themselves being thickly covered with sand ex- 

 ternally. 



The genera recognized are as follows: 



