297 
INTRODUCTORY PAPERS ON ICHNEUMONIDZ.. 
By Joun B. Bripagman and Epwarp A. Fircu. 
No. IL—ICHNEUMONIDAE (continued). 
A CAREFUL study of the foregoing tables will fully bear out our 
prefatory remarks as to the amount of variation existing in this 
somewhat extensive genus. Most of the species occur twice, 
owing to sexual variation; many are mentioned three times; 
I. computatorius and J. varipes oceur four times; and I. lineator 
is sO variable that it occurs seven times, and even in three sections 
(1, 8, and 8). This close affinity, constant variation, or the 
difficulty in rightly connecting the two sexes,—not always easy to 
determine, though the male is generally more slender,—often 
apparently distinct species, makes the genus Ichneumon especially 
puzzling to the beginner. Several teratological varieties of 
Ichnewmon have been recorded and figured. Wesmael records 
three cases of gynandromorphism, none bilateral, but one fairly 
complete: that of J. luctatoriws with its eatensorius female 
(coloured plate, Bull. Ac. Brux., vol. 111., 1836); the other two 
cases are specimens of J. comitator and I. nigritarius which are 
partially gynandromorphous (Bull. Ac. Brux., xvi., pt. 2, p. 378). 
Tischbein describes and figures (Stett. Ent. Zeit., xxii., 428; pl.i., 
fig. 3) a polymelian J. luctatoriws which has two well-developed 
tarsi, each with the normal five joints but one with only a single 
claw, on the right hind tibia, which is one-sixth shorter than the 
normal and left-hand one. In the National Collection there is a 
British specimen of I. impressor (nigricornis) with no areolet in 
the right fore wing: irregular neuration is not rare in the 
Hymenoptera, but had both wings of this Ichnewmon been thus 
curiously abnormal it would probably have long remained a 
unique species (? genus). There is a constant variety of J. latrator 
female with abbreviated wings, which led Gravenhorst to establish 
a new genus (Brachypterus) for it, and Forster included it amongst 
the Pezomachi as Pterocormus means ; this variety and the normal 
type are not uncommon in Britain, being frequently found, like 
many of the Ichnewmonide, under moss or loose bark from autumn 
to spring. ‘This interesting variety, unique in this family, has 
been figured by Stephens, Wesmael, and Vollenhoven (twice). 
Until quite lately there have been but few figures of Ichneumon. 
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