54 THE FERTILISATION OF FLOWERS. [PART II. 
While in Bombus the collecting basket is walled in by many 
irregular rows of stiff hairs, still showing traces of the feathery 
branching of the primitively undifferentiated hairy coat, in Apis 
(5, 6, Fig. 15) these hairs have become simple smooth bristles with 
no trace of feathery branching, and arranged in a few close-set rows. 
The bristles of the tarsal brushes in Apis (¢’ 5, Fig. 15) are arranged 
in regular rows, and much more uniformly than in Bombus (t' 8, 
Fig. 15); and the now functionless tibial spurs, inherited from the 
Sand-wasps, which, with most other bees, they aid in making holes 
in earth, rotten wood, etc., have disappeared from the hindlegs. — 
The collecting apparatus of the hindlegs, which culminates in 
the hive-bee, is peculiar to one of the two main divisions of bees ; 
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Fic, 15.—Last grades of perfection of the pollen-collecting apparatus of the hindleg. 
1.—Right hindleg of Macropis labiata, Pz. 9. Seen from behind and within. 
2,—The same laden with pollen of Lysimachia vulgaris. 
8.—Right hindleg of Bombus Scrimshirianus, K. 8. Seen from behind and within. 
4,—Its tibia, seen from the outside (pollen-basket). 
5.—Right hindleg of honey-bee (Apis mellifica, L. $8). Seen from behind and within, 
6.--Its tibia, seen from the outside. 
Lettering as in Fig. 10. 
No. 1 naturally shows only a side view of the hairs on the outer surface of the tibia and tarsus of 
Macropis. 
in the other division a collecting apparatus is formed by hairs on 
the ventral surface of the abdomen. In these forms, at least in 
our native species, we cannot trace a gradual development of the 
collecting apparatus as in the others; but it possesses the same 
main features in all genera of the group (Heriades, Chelostoma, 
Anthidium, Osmia, Chalicodoma, Diphysis, Megachile) ; so that one 
example will suffice for all. 
The whole or nearly the whole ventral surface of the abdomen 
is covered with a brush of stiff bristles inclined backwards, which 
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