SOCIAL WASPS AND HORNTAILS 73 



in other words, virtually drowned ; on being taken out, 

 it recovered after a while, and at once set to work 

 again at the business of its life, as though there had 

 been no interruption. 



The head of a wasp is a remarkable structure (Fig. 25), 

 and well worthy of a close and attentive examination, 

 if only to see what a 



variety of adornment fi^ f 



is lavished on even 

 minute and otherwise 

 obscure parts of the 

 insect, and to marvel at 

 the number of organs 

 that can be collected 

 into so small a space. 

 The entomologist who 

 wishes to distinguish 

 the different species FIG 25 _ Head of Wa ^ : ^ antemife; 



from one another must clypeus ; e, compound eyes ; m, mandibles ; 

 o, ocelli ; s, coronet spot. 



pay great attention to 



the minutia3 of this part of the insect, because some of 

 the best distinguishing marks are to be found here. In 

 shape the head is something like a triangular cake with 

 the angles rounded off ; it is set on the body vertically, 

 with the base of the triangle placed horizontally, and 

 forming the crown. In front it is slightly convex and 

 behind concave, and it is attached to the thorax only 

 by a small junction in the centre of the hinder surface. 



The apex of the inverted triangle is formed by the 

 meeting of the two exceedingly stout and broad jaws, 

 or mandibles, each furnished on its cutting edge with 

 an inner and an outer row of notches or teeth, separated 

 by a groove. They move laterally, and are in most 

 cases attached by a sort of hinge- joint just below the 



