THE VAGARIES OF COLOUR, ETC. 101 



example of them occurs among the small " key- 

 hole " wasps. All the British species are prac- 

 tically alike in coloration. They may vary in 

 having a greater or less number of yellow bands 

 on the body, but otherwise their distinctions 

 rest on structure. In the females the antennae 

 are slightly thickened towards the apex, but 

 otherwise they are simple. The males, however, 

 are divided into three quite distinct groups. In 

 the first of these, the end joints of the antennae are 

 rolled up in more or less of a spiral (fig. 23, 2) ; in 



12 12 



FIG. 23. FIG. 24. 



the second, the apical joint is turned sharply back 

 like a hook (fig. 23, i) ; in the third, the end joints 

 of the antennae are simple and more or less like 

 those of the female. Now if we examine the legs 

 of the males in the first group we shall find still 

 greater peculiarities ; in two of our species there is 

 a long yellow spine at the extreme base of the middle 

 leg on the little joint by which it articulates on to 

 the body (fig. 24, 2), and a curious pencil of hairs 



