166 BRITISH BEES. 



those which collect it upon the whole limb, viz. the coxa, 

 the femur, the tibia, and first joint of the tarsus, (the 

 femorifera] , and those which gather it merely upon the 

 shank and basal joint of the foot (the cruriferae) . These 

 collectively form a well-defined group, and why Panur- 

 gus should be separated from the brush-legged bees, 

 when it is a most conspicuous instance of the faculty, 

 even more so than any other of the Scopulipedes, I have 

 yet to learn. It is true its mode of collecting closely 

 resembles that practised by the Andrenidce, as does also 

 the furniture for the purpose of its posterior legs, but 

 being essentially collocated with the Apidas or normal 

 bees by its tongue, it fittingly links itself to the other 

 brush -legged Apidae (which have hitherto been placed be- 

 tween the Dasygasters and the Social Bees), by means of 

 the genus Eucera, by reason of its two submarginal cells, 

 the structure of its maxillary palpi, its mode of burrow- 

 ing, and by each being infested by a similar parasite 

 a Nomada, which in accommodation to the size of the 

 sitos is the largest of the genus. Nomada does not 

 occur as a parasite upon any other of the brush -legged 

 bees, or indeed upon any other of the true bees at all, 

 which peculiarity brings these two genera into close 

 contiguity to all non-parasitical Andrenida, all of which 

 have their legs furnished with polliniferous brushes, and 

 upon which subfamily, exclusively of these two instances 

 of Panurgus and Eucera, Nomada is solely parasitical. 



With respect to the two submarginal cells to the 

 wings, nature must have some reason for the limitation, 

 for we find it prevalent also throughout the Dasygasters, 

 or hairy-bellied bees. 



The next very natural group is consistently central. 

 It comprises the cuckoo- bees, which are naked-legged 



