230 AMERICAN HYMENOPTERA. 



its front side, especially toward the distal end. It is slightly 

 excavated longitudinally, on the inner side, for contact with 

 the femur when the leg is retracted. At its apex, on the 

 inner side, is a long and much modified spine (fig. 20, SS), 

 which is denticulated or spinulate on both edges of its distal 

 half. This spine is movable and it covers a deep, fringed 

 excavation on the inner side of the base of the metatarsus, 

 forming an opening through which the antenna may be drawn 

 and cleaned. This combined structure is, therefore, known 

 as the antenna cleaner. The spine or spur has a broad mem- 

 braneous and hyaline extension on its inner side, which is 

 not shown in the figure. The metatarsus is long and slender 

 and, except for its basal excavation, is of nearly the same 

 width throughout. The three segments following the meta- 

 tarsus are shorter for their width in the fore tarsi than they 

 are in the middle and hind tarsi. Each is slightly emargi- 

 nate, apically in the middle, for the reception of the base of 

 the one following it. The fifth segment is nearly as long as 

 the three which precede it taken together. It is gradually 

 widened from base to apex. At its tip is a pair of well de- 

 veloped, curved and deeply cleft claws, between which is a 

 rather sm.a\\ pulvillus (fig. 26, PS). The pulvillus is densely 

 covered with minute ferruginous hairs. Each claw bears a 

 single very long slender spine on the lower side near its base. 

 These two spines probably have a sensory function. The 

 middle coxae are elongate and cylindrical in form and are 

 partly imbedded, sidewise, in the thorax. They are inserted 

 between the lower plate of the metapleuron and the front 

 plate of the metasternum behind and the lower part of 

 the mesothoracic episternum and the mesosternum in front. 

 Each of these coxae bears some long hair, arranged in a single 

 longitudinal line, on its outer side. The femora and tibiae 

 are of nearly equal length, the latter being a very little the 

 shorter. Aside from these differences and the absence of a 

 cleaning apparatus at the tip of the tibia and the more dis- 

 tinctly flattened metatarsi, the mesothoracic legs differ little 

 from those of the prothorax. The second, third and fourth 

 segments of their tarsi are, however, proportionately some- 



