THE TATUA MO RIO . 
153 
The tiers of cells are variable in number ; a rather remarkable 
fact, as the floors are made before the cells are built. In a good 
specimen of this nest in the British Museum there are only 
four tiers of cells. How many tiers are completed before the 
insects begin to affix cells to them, or whether the cells are made 
as soon as the floors are finished, are two points in the history 
of this wasp which have not yet been decided. These floors 
extend completely to the walls, to which they are fastened on 
all sides, and the insects gain admission to the different floors 
i by means of a central opening which runs through them all. 
In Mr. Waterton’s museum, at Walton Hall, are several speci- 
mens of these nests, one of which is opened so as to show the 
interior, as well as the central aperture, the whole of the bottom 
being cut away and raised like the lid of a box. The substance 
of this nest resembles thin brownish pasteboard, and, as is the 
custom with most of the wasp tribe, the cells are placed with 
their mouths downward, the nurses being enabled to attend to 
their charges by remaining on the floor of the next tier of cells. 
Taking one row of cells as an average, I counted twenty-four 
from the central aperture to the circumference, thus giving a 
tolerable notion of the number of cells in each tier. The aper- 
ture is not precisely in the middle, so that some rows of cells 
are necessarily larger than others, but I purposely selected a row 
which seemed to afford a fair average. 
There are also certain British wasps which always make 
pensile nests, though none of them are so complicated or so 
finely constructed as those of the pasteboard wasps of hotter 
climates. 
These are popularly called Tree Wasps, and the best known 
among these pensile wasps is the insect which is sometimes 
known as Vespa Britannica , but which is now named Vespa 
Norwegica, , and may therefore be called the Norwegian 
Wasp. 
Of the species in question Mr. Smith remarks that it is rare 
in the South and West of England, but is not uncommon in 
Yorkshire and plentiful in Scotland. It seems to be a nocturnal 
insect, for a collector of lepidoptera found that when 4 sugaring’ 
