sed by
alcoholic poisoning. It is now sometimes loosely used as equivalent to
the condition of incurable inebriates, but strictly should be confined
to the pathological and insatiable desire for alcohol, sometimes
occurring in paroxysms.

DIPTERA ([Greek: dis], double, [Greek: ptera], wings), a term (first
employed in its modern sense by Linnaeus, _Fauna Suecica_, 1st ed.,
1746, p. 306) used in zoological classification for one of the Orders
into which the _Hexapoda_, or Insecta, are divided. The relation of the
Diptera (two-winged flies, or flies proper) to the other Orders is dealt
with under Hexapoda (q.v.).

The chief characteristic of the Diptera is expressed in the name of the
Order, since, with the exception of certain aberrant and apterous forms,
flies possess but a single pair of membranous wings, which are attached
to the meso-thorax. Wing-covers and hind-wings are alike absent, and the
latter are represented by a pair of little knobbed organs, the halteres
or balancers, which have a controlling and directing function in flight.
The other structural characters of the Order may be briefly summarized
as:--mouth-parts adapted for piercing and sucking, or for suction alone,
and consisting of a proboscis formed of the labium, and enclosing
modifications of the other usual parts of the mouth, some of which,
however, may be wanting; a thorax fused into a single mass; and legs
with five-jointed tarsi. The wings, which are not capable of being
folded, are usually transparent, but occasionally pigmented and adorned
with coloured spots, blotches or bands; the wing-membrane, though
sometimes clothed with minute hairs, seldom bears scales; the
wing-veins, which are of great importance in the classification of
Diptera, are usually few in number and chiefly longitudinal, there being
a marked paucity of cross-veins. In a large number of Diptera an
incision in the posterior margin of the wing, near the base, marks off a
small lobe, the posterior lobe or alula, while connected with this but
situated on the thorax itself there is a pair of membranous scales, or
squamae, which when present serve to conceal the halteres. The antennae
of Diptera, which are also extremely important in classification, are
thread-like in the more primitive families, such as the _Tipulidae_
(daddy-long-legs), where they consist of a considerable number of
joints, all of which except the first two, and sometimes also the last
two, are similar in