CLASSIFICATION OF THE SPECIES. 39 
of the antenne, by which they may be divided into 
two classes. In all the sexes of all three species of 
tree-wasp the scape is yellow in front. In the 
ground-wasps the antenne of the females and 
workers are black all over, only the males having 
yellow scapes. We must not say at once that because 
-a wasp has a yellow scape she never builds in the 
ground, for V. sylvestris seems to build above or under- 
ground indifferently, nothwithstanding her yellow 
scape. And other exceptions are constantly occur- 
ring. But still, as a general rule, the colour of the 
scape in the female Vespe indicates their habits in 
this particular very exactly. 
V. britannica, Plate II, one of the tree-wasps, is 
generally easily recognized by her dark appearance, 
but she has besides some very well marked distinc- 
tive characters. The face is very dark, the bounding 
yellow line of the compound eyes being almost too 
fine to be seen, and the only relief bemg given by 
the scapes, the small corona, and a comparatively 
small portion of the clypeus. This last is divided 
from top to bottom by a broad black line, swelling 
out on either side into something of the figure of a 
spear-head pointmg downwards, the angles being 
more or less acute in different specimens. ‘The corona 
is small, and is divided into two lobes by a deep notch 
both above and below. Alone, of all the species, the 
face of this wasp is quite unmistakeable. 
Turning to the dorsal aspect of the insect, we find 
on the vertex of the head and on the thorax but few 
distinctive marks. For the two yellow spots which 
appear on the metathorax, one on either side, are 
