CHAR A CTERISTICS. 



205 



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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 Scutigeridce 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 antennas 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 coxre of which are of large size : and in one 

 of the genera (Cerniatobius), which forms by itself the family Cermatobiidce, the 

 tarsi of the legs are many-jointed. There are cither 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 



BLACK-BANDED CENTIPEDE, SadiffCra, 



(nat. size). 



