MYiilArODA. 



CHAPTER XV. 



MYEIAPODA. 



Class III. Myriapoda. 



This class is a small one, and includes only the Centipedes and the 

 Millepedes. In all the Myriapoda the head is disii/iH, and not 

 amalgamated ^¥ith the thorax. There is no clear hoimdarii-line 

 between the thorax and the abdomen, both being composed of nearly 

 similar segments. The body (except in the genus I'auropus') always 

 consists of more than twenty rings; and the hinder segments, which 

 correspond to the abdomen, always carry locomotive appiendages, 

 whereas the abdominal rings in Araclinida and Inneeta are always 

 destitute of locomotive a]>pendages. One pair of antennai is present, 

 and the nurnher of the legs is always more than eight pairs. Eesjjira- 

 tion is carried on by branched air-tubes or trachefe. 



In most of their characters the Myriapoda closely lesenible the 

 true Insects, with which, indeed, they are not uncommonly classed. 

 The true Insects, however, always have the head, thorax, and aljdo- 

 men distinct from each othei', and ha\e never more than three ])airs 

 of legs. In most of the Myriapoda the young or "larva;" are more 

 like insects than the adult, since they have only three pairs of legs, 

 or are altogether destitute of feet. In some cases, however, the 

 young Myriapod, on escajilng from the egg, posse.sses nearly all the 

 characters of the parents, exeejit that the number of body-rings, 

 and consequently of legs, is smaller, and increases with ever}' change 

 of skin ("moult"). The class is divided into two leading groujis 

 or orders, represented by the common Centipedes {(Jdlopoda) and 

 Millepedes {Chilognatha). 



The Centipedes (tig. 10"i) are carnivorous in their habits, and the 

 organs of the mouth are adapted for a life of rapine. In addition to 

 the parts of the mouth proper, they have two jiairs of "foot-jaws," 

 of which the second is hooked and perforated for the discharge of a 

 poisonous fluid. The bite of the common European .species is per- 

 fectly harmless to man, but some of the trojiical forms attain a 



