222 THE HYMENOPTERA. 



neck_, which gives it great power of motion. The 

 eyes^ which are placed on the sides of the head^ are 

 generally large^ and in the males of many species 

 they occupy nearly the whole npper surface of that 

 part of the body^ leaving only a space in front for the 

 insertion of the antennae and of the ocelli^ which are 

 almost always present^ and three in number. The 

 antennae are very variable in length and form^ being 

 sometimes short and stout^ or even clavate_, sometimes 

 pectinated, and sometimes long, slender, and tapering. 



The whole body is always enclosed in a hard skin, 

 which is especially firm upon the thorax, the anterior 

 segment of which (the prothorax) is very small, but 

 distinctly separated from the others, whilst the meso- 

 and metathorax are fused into a somewhat oval mass. 

 The six legs articulated to the thoracic segments vary 

 considerably in form in particular groups, but they 

 are generally long and slender, and terminated by 

 five-jointed tarsi. 



The abdomen is composed of a variable number of 

 horny rings, which is even sometimes different in the 

 two sexes of the same species; it is sometimes at- 

 tached to the metathorax by the whole breadth of its 

 base, whilst in the majority, the basal, and frequently 

 also some of the following segments, are greatly nar- 

 rowed, so as to form a thin stalk ; and so slender is 

 this in many cases, that we can scarcely imagine how 

 the mass of the abdomen is supported in its proper 

 position by such a mere thread. Throughout the 

 order, however, the abdomen of the female is termi- 

 nated by a valvular sting or ovipositor, and the essen- 

 tial nature of this organ appears to be the same in 

 all the species, although its structm^e is modified to 

 suit their various necessities; and in certain groups 



