Anthophora pilipes has a very close relative in Anthophora retusa, which also forms large colonies, but it is as a rule less common. These two species are exceedingly alike, in fact it requires some skill on the part of the observer to differentiate their females. They are both black and clothed with black hairs, and both have yellow pollen-brushes, but in retusa the hairs are shorter and not quite of such a deep black as those of pilipes, and the spurs of the tibiæ are pale, whereas in pilipes they are black. The males, however, differ widely, although much alike in colour; in pilipes the feet of the middle pair of legs are clothed with enormously long hairs, the basal joint has a dense fringe of black hairs in front and some long black hairs behind (see [pl. D], fig. 24); in retusa the basal joint of the middle pair of feet have a fan-shaped fringe of black hairs, and the rest of the joints are clothed with longer hairs, but not long enough to be specially noticeable. A. retusa is visited by the same cuckoo as A. pilipes and also by its rare ally Melecta luctuosa, which only differs from armata
([pl. D], 26) in the larger and squarer spots of the body and various small structural characters hardly appreciable except by specialists. The Anthophoras have other parasites besides their cuckoos; one is a beetle, which, however, is rare, and which lays its egg in the Anthophora cells; the other is a very minute member of the Hymenopterous family, whose larva when hatched feeds upon the larva of the bee. Notwithstanding these disadvantages both species are abundant, although retusa is more local than pilipes. A very interesting fact connected with this genus has just been communicated to me by the Rev. F. D. Morice. John Ray, who lived in the seventeenth century, mentions in his book Historia Insectorum (published posthumously in 1710), p. 243, that a large colony of a bee, which from his description was clearly an Anthophora, as he specially calls attention to the great difference between the males and females, inhabited a certain locality at Kilby near "Hill Morton" in Northamptonshire. Mr. Morice, who for many years resided at Rugby, knew Hillmorton, as it is now spelled, well, and tells me that a large colony of Anthophora was in that same locality when he knew it only
a few years ago. Of course there is no proof that it has been there throughout the intervening period, but there seems to be no reason to doubt it, and if so it is a most interesting case of a persistent colony.
BEES AND POLLEN-COLLECTING
Bees whether solitary or social enter flowers for the sake of the honey in their nectaries and the pollen on their anthers. In some cases the flowers automatically deposit pollen on the bees during the operation, which enables them to fertilize other flowers of the same species, but the pollen which the bee requires for its own use has to be worked for and collected on organs specially adapted for the purpose. These vary very much in the different families and genera; they exist only in the females, and, if the males get covered with pollen, as they often do, it is probably more by chance than purpose, and it is doubtful if it is of any value to the brood, although no doubt useful in fertilizing other flowers. All our bees, as has been pointed out before, are clothed more or less with branched or feather-like hairs, which would appear to be admirably adapted for the collecting of pollen.
At the same time some species which have their bodies clothed with branched hairs have simple or spirally grooved hairs on the collecting organ—others collect on very much branched hairs—so that there seems to be no exact relationship between the plumosity of the hairs and their utility in collecting. The collecting brushes are either on the hind legs or, as in some cases, on the ventral surface of the body. In a female Andrena, the hind leg has a tuft of curled hairs near the base of the leg, and a more or less heavy brush on the outside of the tibia or shin (fig. 8). When a female returns after a collecting expedition these specially hairy regions are a mass of pollen grains, and the "beautiful yellow legs", so often remarked upon in some bees, are not always due to the colour of the hairs but to that of the grains of pollen adhering to them. The genera which collect on the under surface of the body have to visit flowers where the anthers lie in such a position that they can transfer the pollen on to it; the pea flower tribe are favourites with them, and also the Compositæ. All this section have long tongues so that they are able to reach the nectaries of
