NATURAL GROUPING OF BREMID/E. 397 



dividing the Bremidae into natural groups was discovered by the 

 late F. W. L. Sladen ('99) who called attention to the fact that 

 the various English species of the genus Bremus employ two 

 very distinct methods of feeding their larvae. Since this short, 

 but epoch-making paper of Sladen ('99) has been overlooked by 

 several workers, and since it forms the chief basis for the present 

 discussion, it seems advisable to quote the two following para- 

 graphs from it. 



'Taking nests of humble-bees and keeping them under observa- 

 tion in specially constructed hives has been a hobby of mine for 

 some years, and it is astonishing what a quantity of interesting 

 information one can gather in this way about the habits and 

 life-history of the dozen or so species that have been recorded 

 from this country, several of which are very common and familiar 

 to every one. It appears that each species has habits and pro- 

 clivities more or less peculiar to itself, and these, if they could be 

 accurately observed and recorded, would help very much in the 

 systematic arrangement of the species, which in this interesting 

 genus is unusually difficult, owing to the lack of easily recognisable 

 structural differences, and to the little reliance that can be placed 

 on colouring. 



"As a result of taking a number of nests it appears that most of 

 the Bombi found in this country may be separated into two 

 groups, on what seems to be a rather important difference in the 

 manner of raising their young. These groups may be conveni- 

 ently named (i) the 'pouch-makers' and (2) the ' pollen-storers.' 

 The pouch-makers form little pockets or pouches of wax at the 

 side of a wax-covered mass of growing larvae, into which the 

 workers drop the pellets of pollen direct from their hind tibiae on 

 the return to the nest from the fields. The pollen-storers, on 

 the contrary, store the newly gathered pollen in waxen cells 

 specially made for the purpose, or in old cocoons specially set 

 apart to receive it, from which it is taken and given to the larvae 

 through the mouths of the nurse-bees as required." 



Thirteen years later, Sladen ('12, pp. 40-44, 152-153), in 

 addition to elaborating the foregoing plan in general, changed 

 the term Pouch-makers to Pocket makers, and further subdivided 

 the latter group into Pollen-primers and Carder-bees. However, 



