ra-tropical Asia, and North and Central America. In habits the
_Lithobiidae_ closely resemble the _Scolopendridae_. They are,
however, comparatively far more agile with their shorter, more compact
bodies and stronger legs. They are mostly of small size, the largest
species, _Lithobius fusciatus_, of south Europe measuring only 2 in.
in length of body. The females do not guard their eggs, but coat them
with soil and leave them to their fate.

SUBCLASS 2, NOTOSTIGMA.--Chilopods with a series of median dorsal
tracheal sacs furnished with tubes dipping into the pericardial blood
space, and opening each by an unpaired spiracle upon the 1st, 3rd, 5th,
8th, 10th, 12th and 14th leg-bearing somites. This characteristic is
accompanied by the complete disappearance of the tergum of the 7th,
either by fusion with that of the 8th or by excalation, and by the
evanescence of the terga of the 2nd, 4th, 6th, 9th, 11th and 13th
pedigerous somites. The preantennal area of the head is not strongly
reflexed inferiorly, and the eyes are large and compound. The maxillae
are long and have a sensory organ, the palpognaths are long, spiny and
composed of five segments, like the primitive Chilopod leg, and the
toxicognaths have their basal segments disunited and independently
movable. Gonopods duplicated in the male.

[Illustration: FIG. 9.--A, _Scutigera rubrolineata_ (after Buffon). B,
Tergum and part of a second of the same enlarged to show the position of
the stigmata o, o; p, hinder margin of tergum.]

This subclass contains the single order Scutigeromorpha and the family
_Scutigeridae_. As in the Lithobiomorpha there are fifteen pairs of
legs, the gonopods are well developed in both sexes and the young is
hatched with only seven pairs of legs. The legs and antennae in the
adult are extremely long and many jointed. In habits as well as in
structure the _Scutigeridae_, of which _Scutigera_ is the best-known
genus, differ greatly from other centipedes. Although they hide under
stones and logs of wood like _Lithobius_, they are not lucifugous but
diurnal, and may be seen chasing their foes in the blazing sun. They
run with astonishing speed and have the power of dropping their legs
when seized. South of about the 40th parallel of north latitude they
are universally distributed in suitable localities. In most species
the body only reaches a length of about 1 in.; but twice that size or
more is reached by