METHOD OF DETERMINING GENERA. 179 



of the posterior tibiae, the 



centime glabrous. 

 Body densely hirsute, spurs to 



all the tibia? BOMBUS (26). 



Body subpubescent, no spurs 



to the posterior tibiae . . . APIS (27). 



It will be desirable to add a few observations to the 

 preceding table to facilitate its use, and because, as 

 many of the characters upon which it is framed are ex- 

 clusively those of the female, it is necessary to point out 

 the differences of their males, that the sexes of the 

 genera may be duly recognized and associated. 



It may be first noticed generally that the antennse, 

 in the males, are not usually geniculated at the scape, 

 which is nearly always the case in the opposite sex, and 

 they are also, with rare exceptions, always longer than 

 those of their females. In Colletes, Prosopis, Dasypoda, 

 Panurgus, Ceratina, Nomada, Melecta, Epeolus, Stelis, 

 and Anthidium, the habit or colouring of the males is 

 so similar to that of the females, that their genus may 

 be thus at once determined, and, in fact, the brief cha- 

 racters in the table will embrace them. 



The male Eucera can be distinguished from those of 

 Anthophora and Saropoda, both by the differences in the 

 number of the submargiual cells of the wing, and by the 

 extreme length of its antennse, whence the genus derives 

 its name. In Andrena and CH'tssa, the males have 

 usually lanceolate bodies. In the latter genus there 

 will be no difficulty in associating the legitimate part- 

 ners; but in Andrena, although general habit will usually 



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