44 
BRITISH BEES. 
sits it, according to the nature of the bee, upon the pos¬ 
terior tibia and planta, or upon the venter. The evi¬ 
dence of this process is speedily manifested by the 
posterior legs gradually exhibiting an increasing pellet 
of pollen. Thus, for this purpose, all the legs of the 
bees are more or less covered with hair. It is the man¬ 
dibles which are chiefly used in their boring or excavat¬ 
ing operations, applying their hands, or anterior tarsi, 
only to clear their way; but by the constructive or 
artisan bees they are used both in their building and 
mining operations, and are worked like trowels to collect 
moist clay, and to apply it to the masonry of their 
habitations. 
The mesothorax, or central division of the thorax, has 
inserted on each side near the centre the four wings, 
the anterior pair articulating beneath the squamula, or 
wing scales, which cover their base like an epaulette, and 
this wing scale often yields a specific character. In 
repose the four wings lie, horizontally, along the body, 
over the abdomen, the superior above, the inferior beneath. 
The wings themselves are transparent membranes, in¬ 
tersected by threads darker than their own substance, 
called their nervures, which are supposed to be tubular. 
These nervures and the spaces they enclose, called cells, 
are used in the superior wing only, and only occasion¬ 
ally, as subsidiary generic characters, and their termi¬ 
nology it will be desirable to describe, as use will be 
made subsequently of it. At the same time, to facili¬ 
tate the comprehension of the terms, an illustrative dia¬ 
gram is appended; but those parts only will be de¬ 
scribed which have positive generic application. I may, 
however, first observe that upon the expansion of the 
wings in flight, the insect has the voluntary power 
