Holmesdale Natural History Club. 51 



the length and density of the hairs on their bodies. There are the Bumble 

 bees, which as we all know are densely covered with long hairs, besides others 

 which resemble them in this respect ; then there are a good many which 

 have a densely hairy head and thorax, and an abdomen more or less 

 banded with pale or white hairs as the case may be, which hairs are often 

 closely pressed down on the surface of the body; others have these 

 adpressed hairs also on the thorax ; others, again, are almost naked, and 

 one has a difficulty in observing hairs on them at all. Now, as a rule, the 

 dense long pubescence like that on the bumble bees is made up of more or 

 less shortly branched hairs, the adpressed pubescence such as that of the 

 abdominal bands mentioned above is made up of the very closely and com- 

 pactly branched hairs. The hairs of the pollen-collecting apparatus, 

 whether on the tibisB or the under side of the abdomen, vary exceedingly 

 in form ; in some species they are simple, in some rigid and branched, in 

 others flexuous and branched, in others rigid and spiral ; and this variation 

 aeems to me to be particularly interesting, especially since in two closely 

 allied species which have the hairs of the thorax almost identical in shape, 

 the hairs of the pollen apparatus may be utterly different. The object of 

 this variation is what I want to discover. It evidently, I think, has some 

 direct bearing on the process of pollen collecting, because it occurs so 

 prominently on the organs set apart for this purpose ; and it is probable, to 

 my mind, that in some way it will be found to correspond with the variation 

 in the flowers from which the bees collect their pollen, or in the nature or 

 ■shape of the pollen grains themselves ; for instance, it is quite possible that 

 those bees which visit flowers whose pollen may be particularly viscid would 

 only require simple hairs to collect it on, whereas those which visit flowers 

 with less viscid pollen might require hairs branched, so as more surely to 

 hold it when received. All this is of course conjecture, but I think it is a 

 subject well worth any microscopist's while to study and try to work out, 

 and I would earnestly commend it to any members of your Club who may 

 be inclined to work at a subject of which so little is known. 



There are yet other hairs which I wish to submit to your attention. These 

 are the hairs with flattened apices ; they occur on the inner side (i.e., the side 

 towards the body) of the hind tibiffi and tarsi, and I beUeve they exist on most 

 of the known species. I have little doubt that they are useful for cleaning 

 purposes, especially for removing the pollen when the bees get to their 

 nests. On the front legs of the bumble bees, and I have no doubt of others 

 too, there are somewhat similar hairs, but the sharp edge is lateral, and 

 not apical, so that the hair resembles a knife instead of a spade. One 

 occasionally sees an insect cleaning itself, and the movements of the legs 

 in that operation would, as far as I can see, exactly bring the sharp edges 

 of the hairs into play, the movement of the hind legs being more vertical 

 than that of the front legs. I feel convinced that I am not over-rating the 

 value of these hair peculiarities ; they have already afforded me a character 

 by which to separate the pollen-collecting bees from the wasps and other 

 sting-bearing Hymenoptera ; for although these had long ago been 



