102 THE VAGARIES OF COLOUR 



on each side of the mouth. In two others, the 

 femora, or thighs of the middle legs, are cut into 

 two deep somewhat semicircular incisions (fig. 

 24, i) a most curious character ; but here again 

 the females have no corresponding peculiarities. 

 There seems to be no explanation known for these 

 vagaries, and yet one feels that there must be 

 some object served by them. If we turn to the 

 bees we shall find that in many species the 

 face of the male is white to a greater or less 

 extent, whereas that character is very rare in 

 the female. The front feet are produced into a 

 wide flattened form in some, in others the middle 

 legs are extraordinarily developed, and provided 

 with tufts of hairs, etc. Another form of 

 male development lies in the form of the head. 

 This is sometimes very much enlarged often 

 varying considerably in this respect in specimens 

 of the same species ; there is often a projecting 

 tooth or spine on the mandible or jaw at its 

 base, or frequently on the cheek just above it. 

 Then in the f ossors the males of the genus Crabro 

 break out into numerous eccentricities ; in some, 

 two or more of the joints of the antennae are 

 soldered together and curved or cut out into curi- 



