The ant is divided into three parts — the head, the thorax,



S6



ANTS AND THEIR WAYS



and the abdomen. The head and thorax in this species are
rough and striated. The thorax is subdivided mlo prothorax,
mesothorax, and melathorax, this last carrying two long and
acute spines. In M. ruginodis the spines are also long. In
M. lavinodis they are short, and the sculpture of the thorax
and head is more delicate than in the two former allied
species. In some species the spines are wanting — e.g. our
house ant, which has received many names ; that which is
most descriptive of its habits is, I think, Diplorhopirum
domestkum. Attached to the three divisions of the thorax
are three pairs of legs, each with haunch, thigh, shank, and
five-jointed foot, which is armed with two toe-claws, which
create a tickling sensation when the little creatures course
over the human skin, and also a spur upon the shank or
tibia, which spur in the foreleg is more largely developed
and very conspicuous, and fashioned into a comb, with
which it cleanses itself and completes its toilet, often
standing erect, in a very grotesque attitude, to effect its
laudable purpose. The abdomen is ovate in form, smooth
and shiny, and composed of several rings. We notice,
further, a very thin waist between the thorax and
abdomen, called the petiole, elegant in form, furnished with
two ornamental globular enlargements called nodes, the
character of which forms a useful guide in the differentiation
of species, the M. scabrinodh having the nodes rugose
striated, the M. ruginodis, rugose, and the M. Icevinodis
comparatively smooth and shining.
