THE CARDER BEE. 79 
ordinary wasp, except that the cells are smaller, and the 
material stronger. But, towards the top, the partitions 
between the cells become thicker, and in consequence the 
cells are fewer. This increased strength is chiefly found 
in the partitions which run perpendicularly, and which 
are so thick, that the hexagonal form of the cells becomes 
obscured, the great object being, not the exact shape of 
the cells, but their ability to bear the weight of the comb 
below. 
The general effect of this modification can be easily 
imitated by taking an oblong piece of linen, rounding the 
corners, and plaiting one end, just as ladies gather in the 
upper part of an apron. The longitudinal folds will then 
represent the perpendicular partitions of the cells, and will 
show how strength is gained without needless expenditure 
of material. The strengthened partitions do not run 
quite perpendicularly, but are slightly irregular, just as 
would be the case with the folds of the linen if it were 
fastened to a branch by the plaited end, and suffered to 
hang loosely. 
The history of Social Insects would be incomplete 
without the mention of several British insects, which are 
plentiful enough, but which are scarcely known as well 
as they deserve. These are the creatures which are popu- 
larly known as Carper BEEs, because they prepare the 
materials for their nest in a manner similar to that which 
is employed in carding cotton wool or heckling flax. 
Several species of Carder Bee are known, all belonging 
to that familiar group of insects called Humble Bees. 
Among these, as among Humble Bees in general, there is 
a great variety of colour, so that the same species has been 
called by different names, even by skilled entomologists. 
For example, in Kirby’s admirable monograph of British 
