AMERICAN HYMENOPTERA. 167 



Segment 1 rounded, with a narrow sulcus; clypeus broadly eniarginate; man- 

 dibles slender; maxillary palpi 4-jointed ; joint 1 of labial palpi stout, 

 less than one-third as long as 2, 3 = 4, 4 oblique ; finely punctured. 



Proclielostoma. 



2. Segment 1 with a wide impunetate concavity; mandibles trid en tate; maxillary 



palpi 4-jointed ; joint 1 of labial palpi one-fifth longer than 2; scopa 



yellowish Ashmeadiella. 



Segment 1 with a narrow sulcus; maxillary palpi 5-joint ; joint 1 of labial 

 palpi two-fifths shorter than 2 3. 



3. Mandibles 4-dentate ; clypeus finely punctured; scopa yellowish; larger. 



Androiiieus. 

 Mandibles 3-dentate; clypeus coarsely punctured; scopa whitish ; smaller. 



Alcidamea. 



Males. 



Section 3 of vein III longer than IIIi ; dorsal segments 7 2. 



Section 3 of vein III not longer than III, ; antenna simple 1. 



1. Segment 1 subtruucate, with a punctate concavity bounded by a salient rim ; 



abdomen with 6 visible segments above, 2 beneath ; ventral segment 1 

 gibbous, produced over middle of 2; dorsal segment 6 entire, clasping 



apex of ventral segment 1 Trypetes. 



Segment 1 rounded, with a narrow sulcus; abdomen with 7 visible segments 

 above, 4 beneath ; dorsal segment 7 with two apical spines and two 

 dentiform lateral angles Proehel osl o ma . 



2. Flagellum simple, short, intermediate joints about one-half as long as the last; 



segment 1 with a wide impunctate concavity; 6 with 4 equidistant 

 teeth, the median ones longer, subtruncate; 7 short; ventral seg- 

 ments 3 Ashmeadiella. 



Flagellum with some joints deformed ; ventral segments 5 ; dorsal segment 1 

 with a narrow sulcus 3. 



3. Joints 4-7 dilated, 8-9 broader than long, 10-13 longer than broad ; segment 7 



broadly rounded, a little dilated, foveate ; ventral segment 1 produced 

 to a spine, 2 broad and concave, 4 with lateral apical angles visible. 



Andronieus. 



Joints 4-12 at least broader than long, 13 produced to a curved point ; dorsal 



segment 6 with lateral apical spines Alcidamea. 



2. MEGACHILIN.E. 

 MEGACHILINI. 

 Females. 

 Mandibles slender, not expanded at apex, tridentate; clypeus excavated, with 

 lateral tubercles; claws with a blunt basal tooth ; stigma long and nar- 

 row ; vein m longer than section 2 of V ; joint 3 maxillary palpi hairy, 

 longer than 1 + 2; joint 1 of labial palpi one-sixth longer than 2. 



Chelostomoides. 

 Mandibles broad at apex 1, 



TEANS. AM. ENT. SOC, XXIX. APRIL, 1903 



