20 



HIND-LEGS OF BEES. 



[CHAP. 



necessity of using their mouth for certain domestic 

 purposes has limited its specialisation in this parti- 

 cular direction. 



If, again, we examine the hind-legs of bees, we 

 shall find gradations similar to those already men- 

 tioned in the lower lip. In Prosopis (Fig. 21) they 

 do not differ materially from those of genera which 

 supply their young with animal food. Portions of 

 the leg, indeed, bear stiff hairs, the original use of 



FIG. 21. 



FIG. 23. 



FIG. 24. 



FIG. 21. Left hind-leg of Prosopis. FIG. 22. Lef^hmd-leg of Sphecodes. 



"*""" ' J -let 



FIG. 23. Sphecodes. 



FIG. 24. Right hind-leg of Halictus. 



which, probably, was to clean these burrowing insects 

 from particles of sand and earth, but which in Pro- 

 sopis assist also in the collection of pollen. 



Fig. 22 represents the hind leg of Sphecodes (Fig. 

 23), a genus in which the tongue resembles in form 

 that of Halictus. Here we see the hairs decidedly 

 more developed, a modification which has advanced 

 still further in Halictus (Fig. 24), in which the de- 



