METHOD OF DETERMINING GENERA. 
1 77 
Three submarginal cells to the wings. 
Abdomen truncated at base . . . 
Abdomen ovate. 
Abdomen entire at apex; maxil¬ 
lary palpi as long or longer than 
the maxillae. 
Abdomen entire at apex ; maxil¬ 
lary palpi half the length of the 
maxillae. 
Abdomen with a vertical incision 
at the apex. 
Colletes (l). 
Andrena (4). 
ClLTSSA (5). 
Halictus (7). 
Posterior tibiw without hair to convey pollen. 
Two submarginal cells to the wings . Prosopts (2). 
Three submarginal cells to the wings . Sphecodes (3). 
Apid.e (Normal Bees). 
Tongue as long or longer than the maxill.e, in¬ 
flected beneath, and covered by the maxilla in 
repose. 
Without polliniferous organs. 
Two submarginal cells to the wings. 
Abdomen at apex rounded . . . 
Abdomen at apex conical . . . . 
Three submarginal cells to the wings. 
Abdomen lanceolate. 
Abdomen subtruncate at base. 
Abdomen obovate, thorax glabrous 
Abdomen subconical, thorax hir¬ 
sute . 
Entire body densely hairy . . . 
Stelis (17). 
CcELIOXYS (18). 
Nomada (14), 
Epeolus (16). 
Melecta (15). 
Apathus (25). 
With polliniferous organs. 
Pollen conveyed on the venter. 
Two submarginal cells to the wings of all. 
