CHAR A CTERISTICS. 
205 
in structure. Breathing is effected by tracheal tubes, which open by means 
of stigmata, placed almost always upon the pleural membrane of the segments. 
Centipedes are divided into two subclasses—Anartiostigma, or those with 
unpaired dorsal stigmata, and Artiostigma, or those with paired lateral stigmata. 
In the former group, which contains the single family Scutigeridcc and the 
genus Scutigera, the head is furnished with a pair of large, compound, faceted 
eyes, the widely separated antennae are exceedingly long and thread-like; and 
the body, although composed of fifteen segments, has only eight dorsal plates, 
all of which except the last are furnished in the middle of the hinder border 
with a single large respiratory stigma. The first pair of maxillipedes consists 
of five segments, and the coxae of the second pair, or poison-jaws, are not 
united; the legs are very long and their tarsi 
composed of a multitude of minute segments. 
The species of the genus Scutigera are distributed 
over all tropical and subtropical countries. Most 
are of small size, with the body only about an 
inch in length, but in India and China there are 
species (S. longicornis and S. clunifera ) which 
may reach a length of several inches. The 
majority are vividly coloured with black and 
yellow stripes or spots, and all are remarkable 
for their extreme agility, and the readiness with 
which, when handled, they part with their legs. 
None are indigenous to Britain, but the common 
South European S. coleoptrata has been introduced 
into a paper-mill near Aberdeen, where, protected 
by the artificial heat, it has become established, 
and breeds. Unlike the rest of the centipedes, 
which habitually shun the light, the species of 
Scutigera may be seen in their native haunts 
darting about and catching insects regardless 
of the blazing sun. They are, however, by no means strictly diurnal, and the 
American S. forceps will come out in numbers at night to feed on flies. 
In the Artiostigma the stigmata are paired, and open upon the pleural 
membrane of all or some of the segments. There are the same number of tergal as 
of sternal plates; the eyes, when present, are not faceted, but consist of simple 
ocelli; the antennse are stouter and not thread-like; the first maxillipedes consist of 
four segments, and the coxae of the poison-jaws are united. The subclass contains 
the orders Lithobiomorpha, Scolopendromorpha, and Geophilomorpha. The first 
of these approaches the Anartiostigma in many characters, particularly in being 
furnished with fifteen pairs of legs, the coxae of which are of large size; and in one 
of the genera ( Cermatobius ), which forms by itself the family Cermatobiidce, the 
tarsi of the legs are many-jointed. There are either six or seven pairs of stigmata, 
situated upon the first, third, fifth, eighth, tenth, twelfth and fourteenth leg¬ 
bearing segments in Henicops and Cermatobius, while those on the first have 
disappeared in Lithobius. In the latter genus, which with Henicops makes up 
\ 
<, / 
V 
BLACK-BANDED CENTIPEDE, Scutigera, 
(nat. size). 
