14 INTRODUCTION. 



apex of the wing below the radius, which is termed for brevity 

 the cubitus or cubital uervure, though it is found by analogy with 

 other Hymenopterous families that the cubitus does not extend 

 beyond its incomplete apex in the centre of the first discoidal cell, 

 known as the nervelet or ramellus. Two short nervures, the 

 intercubiti or submarginal veins, connect the cubitus with the 

 radius and these are always present in the ICHNEUMONES PENTA- 

 OONI, though the external is frequently wanting in the DELTOIDEI ; 

 these two nervures constitute the sides of the areolet, the apex of 

 which is that part of the radial nervure between them, its base 

 being formed by the two portions of the cubital nervure from 

 between which is emitted the second recurrent nervure running 

 straight down from the areolet to the anal nervure or nervus 

 parallelus. 



These nervures divide the wing into very distinct cells : the 

 three nearest the radix are the basal ; the radial is above the 

 radial nervure ; below it are two or three cubital cells, of which 

 the areolet is the central ; below the cubital are the two discoidal 

 cells, of which the inner only is referred to in descriptions ; and 

 below these again are the brachial cell on the inner side and the 

 anal cell at the lower extremity of the wing. 



The ueuration of the lower wing is now much utilised for the 

 grouping of both genera and species, and I have raised the whole 

 disposition of our PIMPLIDES upon this foundation, with, I trust, 

 remarkably natural results. Here we find a median nervure and 

 a posterior nervure, connected by a first recurrent or nervellus, 

 which emits from its outer side a distinct nervure to the margin 

 of the wing. Further from its base the median is connected with 

 the radius by a second recurrent nervure, the length of which 

 compared with that of the radial (from their junction to the base 

 of the radius) is employed for specific grouping. The nervellus or 

 first recurrent nervure is said to be antefurcal if its upper 

 extremity be nearer the radix than its lower, to be continuous or 

 opposite if both extremities be equidistant therefrom, and to be 

 postfurcal if the lower extremity be the nearer thereto ; in the 

 first of these cases the external nervure (when present) is emitted 

 from below the centre of the nervellus, in the second from its 

 centre, and in the last from above its centre, always at the point 

 of angulation or geniculation. The cells of the hind wings furnish 

 no features. 



CLASSLFICATION. 



In the first volume upon Hymenoptera of the present series, 

 Col. Bingham divided them into two main divisions, those with 

 the abdomen sessile, the Sessiliventres, and those with a more or 

 less distinct petiole, the Petiolata ; and the latter he subdivided 

 into Parasitica and Aculeata. Prof. Forster in 1862 and 1868 



