6 



GENERA OF HYMENOPTERA. 



^ •• 



The Le(4S (fig. 6) are generally long and slender, often short and 

 robust, pubescent, bristled or spined, sometimes more or less deformed. 

 The first joint, or that by which they are attached to the body, is 

 called the coxa (^a) and is variously shaped and rarely spined; at the 

 extremity of the coxa and between it and the femur is a small piece, 

 often two-jointed, called the irochmter (b), this is usually short and 

 small, although in the ditrocha groups it varies considerably in form 

 and length. The first long piece of the legs is called the thigh or 

 femur (c), and following it is the tibia (d); at the extremity of 

 the latter are (me or two movable spines called tibial spurs (e), which 

 are, however, sometimes absent. Following the tibia is a series of 

 joint'i, generally five in number, constituting the foot or tarsus (f ), 

 the last joint usually bears two daws (g), either 

 simple, toothed or cleft, and often furnished at 

 their base within with a membranous or cushion- 

 like appendage called puhillus, which is occa- 

 sionally much enlarged and sometimes wanting. 

 These parts of the legs vary greatly in the dif- 

 ferent families, being fitted either for walking, 

 digging or collecting pollen ; in the latter form 

 they are furnished with more or less dense hairs, 

 the tibia and base of tai-sus being flattened and 

 dilated ; those formed for digging are robust and 

 bristly or spinose. The femur is often r<)bust, 

 and sometimes spined beneath, and in some Chalcids the posterior 

 pair is enormously developed and denticulate beneath ; the tibia and 

 tarsus also vary much in structure ; in some genera of Proctotru- 

 pidae, the anterior tarsus is terminated by curious large reflexed 

 claws which open and shut somewhat like those of a lobster, while 

 in some of the males of the leaf-cutting bee, Megachile, it is broadly 

 dilated and fringed w'th long hairs; these and other modifications 

 of form are consequent upon diversity of economy. 



The Abdomen (figs. 7 and 8) is exceedingly variable in the num- 

 ber of its segments, especially in the ditrocha groups, while in the 

 Ants, Wasps and Bees, it is com])osed of seven segments in the males 

 and six in the females. In form it varies greatly, being ovate, glo- 

 bose, clavate, cylindrical, fusiform, sickle-shaped, knife-shaped, etc., 

 and in some species it is sessile (fig. 7), i.e. connected with the thorax 

 by quite or nearly its entire breadth, and in others petiolate (fig. 8), 



Fig. 6. 



a, coxa ; b, trochan- 

 ter ; c, femur ; d, tibia ; 

 e, tibial spurs ; f, tarsus ; 

 g, tarsal claws. 



