1 LIFE-HISTORY OF BOMBUS 43 
The underground pocket-makers, namely, vwder- 
atus, hortorum, and latretllellus, and probably also 
distinguendus, a close relation of /atrez/lellus, prime 
their egg-cells with pollen, placing a little pollen in 
the bottom of each egg-cell constructed, and laying 
their eggs upon it, and thus they preserve another 
trace of the primitive feeding-method of the solitary 
bees. These four species form a natural group, 
which I propose to call “pollen-primers.” They are 
all large, with long heads and long tongues. 
The pocket-makers, at least B. ruderatus, der- 
hamellus, agrorum, and helferanus, make, as a rule, 
only one poilen-pocket for each bunch of larve, but, 
under certain conditions, they may make two or 
three. When many larve are being reared by a 
small staff of workers, the pockets are small, and 
the pollen that is placed in them is plastered on to 
the wall covering the larve, from which it quickly 
disappears, being no doubt consumed almost im- 
mediately ; but when the population is greater, and 
the weather being fine, pollen is gathered in plenty, 
the pockets are large and cup-shaped, and contain 
during the day a shallow store of pollen, the surface 
of which is concave. Ina nest of derhamellus that 
I took on July 2, 1911, in the height of prosperity, 
the pollen-pockets or cups were very large and of 
an oval shape, several of them measuring 2 in. 
long by } in. wide; they were, however, quite 
shallow, the depth of the pollen in them at the 
centre being only about # in., and there was 
only one pocket to each bunch of larve. When 
