A Short Sketch of the Ichneumons. 123 
adjacent to the anterior margin in the outer half of the wing. 
Now, the species of AZzcrogaster have an irregular, hexagonal, or 
heptagonal, sub-marginal cell just beneath the dark spot in the 
anterior margin. In other genera there is also a triangular cell 
outside, which is here absent. Body bright black, the hinder 
edge of the first two segments of the abdomen being lighter ; 
bases of wings covered with yellow hairs; legs, reddish yellow, 
with the exception of the hind pair and the tarsi of the others, 
which are black. 
Our next example is taken from the typical genus of the 
group, of which two hundred species are found in Germany, and 
is known scientifically as Bracon immutator. 
It is a very small insect, the entire length from head to tail 
being only three millimetres. The head and thorax are black, 
while the abdomen is reddish yellow, with a broad black band 
down the back, and the legs are reddish yellow, black at the base, 
and with brown extremities to the tarsi. The ovipositor exceeds 
the abdomen in length. 
On the buds of oak trees, about June, will often be seen 
numbers of large, round galls, commonly called oak apples, 
yellowish in colour, and varying from the-size of a cherry upwards. 
If one of these be cut open it will be found to be more or less 
spongy in texture, and to consist of numerous chambers contain- 
ing the larvze of a small insect belonging to the Cynipidze, whose 
name is Andricus terminalis. Yet the Bracon spends its larval 
state in these galls, living parasitically upon the maggots inhabit- 
ing them. Other species of Aracon are parasitic upon the larvee 
of beetles. 
We now pass on to the second great group: the ICHNEU- 
MONITES, or true Ichneumons, of which no less than rrgo kinds 
are known to inhabit Great Britain alone. According to Francis 
Walker’s “Synopsis of the Ichneumonites,”* the European 
forms are classified under six families :—OpHIoNID&, TRYPHON- 
IpD#, Basstp#, PIMPLIDA, CRYPTIDAZ, and ICHNEUMONID-. 
Holmgren includes the genera, Lassus and Metopius, which 
according to ‘Taschenberg + constitute the Bassip#, in the 
TRYPHONID#. On the other hand, many writers place the genera, 
Lxetastes, Banchus, and Scolobates, in a separate family; the 
BANCHID#£ distinguishing them from the OPHIONID# by their 
sessile or sub-sessile abdomen, and this arrangement is followed 
* Translation of synoptical arrangements of some European families and 
genera of Hymenoptera. (London: E. W. Janson, 27 Museum St. 1874. 
pp. 48.) 
" “+s Die Hymenoptern Deutschlands (Bremen: Verlag von M. Heinsius. 
Preis 4 M., 50 pf). 
