40 THE CANADIAN ENTOMOLOGIST. 



III5 ; a arcuaie, about lour times as long as section 1 of IV ; m 

 about as long as V, ; facial fovese linear 3 black, at least the bases 

 of tibite yellow ; nearly bare ; no scopa ; 

 Prosopis in ( i ) Prosopididty. 



Submarginal cells 3, 111 as long as III4 + III5; stigma middle-sized; cell 

 Illi+o ^^'ith apex bent away from costa ; vein IV3 about middle 

 of cell III5 ; a only a little longer than section i of IV ; ;// longer 

 than Vj ; facial foveas clavate or oblong ; black, abdomen with 

 pubescent fasciae ; pubescence ordinary ; femorilegid, scopa 

 plumose, on trochanter, femur and lower border of tibia ; 

 Colletes in (2) CoUetidae. 



Submarginal cells 3 ; labrum wider than long, not concealed by 

 mandibles, except sometimes at apex; 1. p. 1-2 flat 2, 



Submarginal cells 2, III and IIIi+s, subequal; labrum longer than 

 wide, base usually concealed by mandibles, apex often showing 

 beyond them ; mandibles at least bidentate ; 1. p. i usually shorter 



than 2 b. 



b. Trypetoidea. 



Claws cleft, inner tooth subapical ; vein a usually before Vj; IVg 

 rarely before III4 ; scutel surpassing postscutel ; abdomen with 

 coloured ornaments ; Afit/iidiince in. . . '. (3) Stelididte. 



Claws simple, sometimes with a basal tooth ; vein a usually beyond 

 V, : IV2 always before IIIi; scutel rarely surpassing postscutel; 

 abdomen usually with pubescent fasciae (4) Megachilidse. 



Apex of segment 6 obtuse, without a spine or mucro d. 



Apex of segment 6 with a spine or mucro, a little concave before the 



point ; m. p. 6 c. 



c. Ceratinoidea. 



Cell III longer than III5, equals III, ; stigma large; cell III5 strongly 

 narrowed above ; vein a arcuate ; IV., near apex of cell III5 ; 

 apex of segment 6 mucronate ; no malar space ; mandibles triden- 

 tate ; blue-green, clypeus, tubercles and knees each with a white 

 spot ; nearly bare ; femorilegid, scopa simple, on anterior faces of 

 femur and tibia, thin on lemur; 1. p. 8:7; 5-9 mm ; Ceratina 

 dupla in ^ (5) Ceratinidae. 



Cell III shorter than III5 ; stigma obsolete ; cell III1+2 longer than 

 2nd IV.; III4 as large as III 4- III:,; III5 narrowed to a point 

 above; vein w longer than Vj ; IV3 opposite III5; IV, beyond 

 middle of cell III4; ocelli large, in a triangle on the front; a 



