17 
sometimes presents good specific characters in the matter of its length 
compared with its width, and of the length, respectively, of its basal 
and apical cross veins. In a few species the relative length of the 
discal cells of the hind wings is of importance. In general, however, 
the neuration of the wings of the Xematines (I refer here more particu- 
larly to the genera developed from the old genus Xematus) is strikingly 
uniform — so much so that repeatedly in the descriptions reference is 
made to what is termed normal venation. This venation will be under- 
stood by a reference to the figure which is drawn to represent such 
venation, and, briefly, consists in the intercostal cross nerve being 
inclined and about its own length anterior to the basal nerve ; the sec- 
ond recurrent being received well within the second cubital cell; the 
third cubital more than half as wide at base as at apex and about 
twice as long as wide at base; the upper discoidal cell of the hind wings 
exceeding the lower and about twice as long as wide. The stigma 
varies considerably in different genera, and also within the limits of 
species. This variation relates to its width compared to its length and 
the character of its apex, whether suddenly or rather obtusely pointed, 
or distinctly acuminate, and also in the character of its lower border, 
whether regularly circularly rounded or nearly straight or more or less 
angulated. 
The features of coloration, which have hitherto been used almost 
exclusively in the differentiation of species, are often constant and fur- 
nish reliable characters, but can not be implicitly relied upon. For the 
ready separation of species and for use in synoptic tables, color will 
always be more valuable than structural characters, especially to the 
beginner (see p. 23). The surface characters of the species, such as 
punctuation and hairy vestiture, are of both specific and generic value, 
but are less striking and significant in this subfamily than in most of 
the other divisions or in other families of Hymenoptera. 
Secondary sexual characters. — The correct association of the males 
and females, in the absence of breeding records, is a difficult matter, on 
account of the striking variation in the sexes in shape, structure of 
certain parts, and particularly in coloration. The most important sec- 
ondary sexual characters are : Color, the male being usually much darker 
than the other sex; form, the male in general being much more elongate; 
and shape of antennae, which in the male are commonly very much longer 
than in the female and frequently compressed basally. 
CLASSIFICATION. 
The following characteristics distinguish the Xematina? from allied 
groups: Antenme 9-jointed, usually elongate, slender, tapering, rarely 
with processes on basal joints, frequently more elongate in the males 
than in the females, and somewhat compressed; anterior wings with 
simple, seldom-divided radial cell, in which latter case the second 
cubital receives both recurrent veins; basal nervure converging with 
13449— No. 3 2 
