192 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxiii. 



the lateral edges; labial i^alpi 2-jointed; maxillary palpi l-jointed; 

 tongue reaching to or beyond the middle of the abdomen. 



Family III. EuGLOssiDiE. 



3. Front wings with tivo cubital cells, the second sometimes incomplete 5 



Front wings with tJiree cubital cells. 



Eyes extending to or nearly to the base of the mandiljles, the malar space 

 wanting, or at most not longer than the jiedicel of antennae 4 



Eyes not nearly extending to the base of the mandibles, the malar space large, 

 distinct, longer than the pedicel, and first joint of flagellum united. 

 Marginal cell very long, as long or longer than the three cubital cells 

 united; body rather densely pubescent; abdomen broadly oval or 

 oblong, flat beneath, convex above; female without corbiculte or 

 polliniferous scopa; male with eyes frequently strongly convergent 

 above, the genitalia, squama, and lacinia alwaj's membranous. 



Family IV. Psithyrid.e. 



4. Labrum large, free, convex, or inflexed. 



Marginal cell neither especially long nor narrow, rarely longer than the first 

 two cubital cells united. 

 Female with a dense polleniferous scopa on hind tibiae and tarsi; body 

 clothed with a dense pubescence; maxillary palpi 2- to 6-jointed. 



Family Y. Anthophokid.e. 

 Female tv'dhout a polleniferous scopa, at most with a thin, sparse fiocculus 

 on hind tibiae and tarsi; body most frequently bare, or nearly; the 

 pubescence, if any, short and sparse, rarely densely pubescent; 

 species often metallic or rufous and black, the abdomen usually 

 ornate, with white or yellow maculae or bands. 



Family VI. NoMADiDiE. 

 Marginal cell 15ng and narrow, usually as long or longer than the three cubital 



cells united. 

 Hind tibiae and tarsi with a sparse pubescence, but vnthout a distinct scopa; 

 maxillary palpi 4- to 6-jointed; body usually metallic or submetallic, 

 nearly bare; abdomen elongate, subcylindrical, the segments more 

 or less constricted at sutures. Small species. 



Family VII. CERATiNiDiE. 



Hind tibiae and tarsi with a dense scopa; maxillary i^alpi usually 4- to 6-jointed 



(rarely wanting); thorax more or less densely pubescent, or at least 



laterally; abdomen not elongate, oblong-oval, with a ventral scopa; 



eyes in males often convergent above.. Family VIII. Xylocopid^. 



5. Labrum large and free, uncovered; maxillary palpi 4-, 5-, or 6-jointed (rarely want- 



ing); body densely pubescent; ventral scopa present, the hind legs 



with a dense scopa. 



Marginal cell neither long nor narrow Family V. Anthophorid^ (part). 



INIarginal cell very long and narrow Family VIII. Xylocopid.e (part). 



Labrum not large and free, most frequently entirely covered by theclypeus {Megd- 



chilidx); or, if sometimes visible, then strongly inflexed {Stelididx). 

 Aljdomen in female ivith a ventral scopa; labrum entirely covered by the 



clypeus Family IX. Megachilid^. 



Abdomen in female without a ventral scopa; labrum more or less visible, not 



entirely covered by the clypeus, strongly inflexed. 



Family X. SxELiniDiE. 



6. Labium, t)r tongue, short, laroad, ol)tuse or emarginate at apex, never acute medi- 



ally; hind femora with or \vithi>ut a distinct pollen brush or floc- 

 culus 7 



