LIBRARY

COLEOPTERA 623
mented but the number may vary from one or two to six or even 27 segments
in rare cases; remarkably developed in males; free or resting in
grooves in the prosternum; setiform, filiform, moniliform, clavate, capitate,
serrate, flabellate, geniculate, and lamellate.
Mouth parts - typically biting, the primitive type; many forms feed only
on liquids. Clypeus - divided or reduced; labrum - variable; absent in
weevils. Mandibles - hard, strong for biting and chewing, crushing; and
piercing and sucking; may be enormously developed in the stag beetles
and longicorns; usually move horizontally, but act vertically in certain
weevils. Maxill;e -large, usually bilobed or toothed. Galea - may be
two-segmented and palpiform. Maxillary palpi - three- to five-segmented
(normally four-segmented); greatly developed in a few families.
Labium - entire or rarely divided. Mentum - conspiCuous. Submentum
- distinct or fused with gula. Gula - well developed in many. Ligulavariable;
entire or lobed. Labial palpi - one-, two-, or three-segmented
(normally three-segmented).
Thorax - Well developed and divided by many distinct sutures.
Prothorax - distinct, usually free, narrower than or as wide as the mesothorax;
pronotum a single sclerite.
Meso- and metathorax -large, closely fused and separated into definite
sclerites by distinct sutures.
Legs - variable, usually strong and frequently long and slender; modified
for walking, running, jumping (enlarged hind femora), digging (fossorial
forelegs), and swimming (hairs and spines on middle and hind legs).
CoxaJ -large, plate-like, conical, or globular; simple or laminate; contiguous
or variously separated; cavities open or closed behind; shape and position
important in classification. Trochanters - single Or double, with
basal part, or trochantin, attached to first two pairs of coxa! in certain
species. Femora - may be enlarged for jumping. Tibi;e - modified for
many uses; rounded or flat and toothed; spurs usually present; swimming
hairs present in aquatic forms. Tarsi - one- to five-segmented, normally
five, but may be heteromerous (5-5-4); segments I and IV often minute,
sometimes absent; segments round or pad-like, smooth or hairy. Clawssimple
or complicated (pectinate or cleft); single or paired.
Wings - remarkable because of the hard or leathery fore pair or elytra which
are useless in flight but afford protection to the body, Elytra -long and
covering abdomen or brachypterous; smooth, polished, granular, striated,
punctate, scaly, or hairy; sometimes fused and uniting in a line down
middle of. dorsum or separated posteriorly. Hind wings - one pair;
present, atrophied, or absent; large; membraneous, with few veins; usually
folding longitudinally and transversely.
Spiracles - one pair between prothorax and mesothorax and one pair on
the metathorax.
Abdomen - normally IO-segmented; segment I atrophied; sternites 3 to 9
visible; terminal segments or pygidium constricted, elongated and retractile