12 BULLETIN 45, UNITED STATES NATIONAL MUSEUM. 



tboru.s. By some autlioiitics it is cousideiecl a sclerite of the meta- 

 thorax. Fij;. /// is the tej^iihi or wing scah* of front wiiij". The meso. 

 pleuroii (Fig, inp) is eoniposed of episternnm ami epiiiieroii. The meso- 

 sternura is undivided and \a fre(piently not separated from the ])leural 

 sclerites. 



The metathorax. or third division of tlie tliorax, sni)]>orts the hind 

 wiugs, liind h»gs. and the al)dojnen, and it also is (piite variable in 

 length, shape, and seulpture. The sides (Fig. infp) are termed the 

 metapleura, and the selerite (Fig. .s7>) extending ol)li(xnely forward 

 from the insertion of the hind legs to the base of the hind wing and 

 behind the mesoplenron is the metepisterniim ; the npi»er surface (Fig. 

 mn) is the metanotum. Fig. up nqn-esents the position of the spiracles, 

 while ihn shows the insertion of tlu^ hind wings. 



Tlu! other normal sclerihvs arc^ not differentiated. 



TiiK wi\c;s. 



In shape and neuration, the wings exhibit the greatest diversity, and 

 are of i)rimary importance in «;lassitication. As a rule, the hind wings 

 are veinless or the neuration is meager (PI. i, Fig. 5), the highest de- 

 velo]>ed having but a single basal cell. They are rather broad and 

 with a distinct lobe in the Bethyliuiic, Endwiemiuse, and th(^ Dryinime; 

 broad in the Froct<>tryin;e, but without a distinct lobe; while in the 

 other groups they are much narrowed toward base, and not especially 

 widened toward apex, the apex being sometimes acute. The front 

 wings are entirely veinless in only a single tribe, the Platygasteriui, 

 although another tribe, the Inostemmini, in the same subfamily, and a 

 few genera in another subfamily, the S(^elioninje, are almost veinless, 

 having only a submarginal vein terminating in a small knob or stigma. 



The neuration of the anterior w ings reaches its fullest development 

 in the Bethyliuie, Embolemina'!, Dryinina^, and Ilelorina', although even 

 in these groups there are genera with almost veinless wings {Cephalono- 

 mia, etc.). 



The neuration of the tirst three of these groups mentioned more 

 closely resembles that of the (Jhrysididic and Scoliidje; the Ilelorina; 

 and some genera in other groups that of the Braconidje; while some 

 genera in the Scelioninse closely approach that of the Chalcidida>. 



The great variation in the shape of the wings and the peculiarities 

 of venation are fully brought out in the plates; but as the neuration, in 

 connection with other characters, is of primary importance in a sys- 

 tematic study of the family, it is important that the horismology of 

 the wings be fully understood. 



In Figs. 4 and 5, on Fl. i, by the use of the front wing of Pristocera 

 atra Klug. and the hind wing of a belytid, as being the most special- 

 ized in the group, and, with the explaaatiou given below, the tecbnical 

 terms may be easily acquired. 



