74 MYRIAPODA. 



antenna, generally regarded as ministering to the sense of touch, 

 but which are probably connected with other perceptions unin- 

 telligible to us. 



The air required for respiration is taken into the body through 

 a series of minute pores, or spiracles, placed on each side along 

 the entire length of the animal, and is distributed by innumer- 

 able ramifying tubes or tracheae to all parts of the system. The 

 number of segments, and consequently of feet, increases progres- 

 sively with age a circumstance which remarkably distinguishes 

 the Myriapoda from insects properly so called. There are two 

 families belonging to this class the Millepedes, or Julidse, which 

 feed on vegetable substances, and the Scolopendridae, or Centi- 

 pedes, which are carnivorous and rapacious. 



The Millepedes* (Julus) are distinguished by their nearly cylindrical 

 form (Fig. 67), their slow gliding motion produced by the alternate action of 

 their very numerous little feet, sometimes more than a hundred in number, 

 and their habit of rolling themselves into a close spiral when touched. They 

 resort to damp and dark places, lurk under stones and moss, and are still 

 more commonly found beneath the bark and in the wood of decaying trees. 

 They are perfectly harmless, and feed entirely on decomposing vegetable 



FIG. 7. Jri.rs. 



materials. For this purpose their mouth is furnished with a pair of stout 

 horny jaws, which move horizontally, and are provided at their cutting edges 

 with sharp denticulations, so as to render them effective instruments in 

 dividing the fibres of rotting wood, or the roots and leaves of decaying plants. 

 Most of them emit a very rank disagreeable odour. The female Millepede 

 deposits her eggs, which are very minute, in the earth, or in the earthy powder 

 of decayed wood. The young, when first hatched, are quite destitute of limbs, 

 and have much the appearance of microscopic kidney beans. In the course 

 of a few days, however, they throw off their first skin, and make their appear- 

 ance, divided into about eight segments, of which the three that immediately 

 follow the head have each a pair of legs. In a few days more, a second moult 

 takes place ; the body is enlarged, the number of segments increased, and the 

 number of limbs augmented to seven pairs on the segments succeeding the 

 head. At the end of a month, or thereabouts, after another change of clothes, 

 the young Millepede appears with twenty-six pairs of feet, and so the process 

 of exuviation is again and again repeated, until the creature arrives at its 

 mature condition. 



The Centipedes f (Scolopendra) (Fig. 55) are much more formidable 

 creatures than the Millepedes : they have a broad flattened body, composed 

 of about four-and-twenty segments, to each of which is appended a pair of 



* Mille, a thousand ; pcs, a foot. f Centum, a hundred ; pes, a foot. 



