C Sie) 
the extent and direction of the nervures to which the 
references are made. 
The contour of the wing is formed by—a. the costal 
nervure, which forms the anterior margin; 6. the apical 
margin, which has no nervure accompanying it; and ¢. the 
posterior margin, which also is without a nervure—it is along 
this margin that the little hooklets are placed which connect 
the superior and inferior wings together in flight. The 
nervures found upon the superficies of the wing are the fol- 
lowing: d. the post costal nervure ; e. the externo-medial 
nervure; f. the anal nervure; g. the transverso-medial 
nervure; h. the radial nervure; i. the cubital nervure ; 
k. the discoidal nervure; 1. the sub-discoidal nervure ; 
m. the transverso-cubital nervures—these vary in number in 
the genera, from one to three being found; 2. the recurrent 
nervures—these also vary in number, there being either one 
or two, in all the British genera there is one; s. the stigma, 
which appears to be a dilatation of the cubital nervure. The 
spaces indicated by numbers show the cELLs or arez found 
upon the surface of the wing: 1. the costal cell; 2. the 
externo-medial cell; 3. the interno-medial cell; 4. the anal 
cell; 5. the radial or marginal cell—when this is crossed 
by a nervure there are either two marginal cells, or the one 
is appendiculated, according to the situation of the nervure 
dividing it, whether it be placed towards its centre or its apex; 
6—9. the cubital, or swb-marginal cells—these vary from one 
to four according to the number of the transverso-cubital 
nervures which cross the space enclosed between the radial 
and cubital nervures: when the latter does not reach the 
apical margin, the boundary cell is called incomplete; and 
if either of the transverso-cubital nervures furcate after 
quitting the radial, the cell enclosed by the fork is called 
petiolated, as in Miscophus, Nysson, Cerceris, Alyson, and 
c 
