MYRIAPODA. 



A, ) which are very minute, are deposited in the earth or vege- 

 table mould in which the Julus is usually met with. When first 

 hatched, the young Myriapod is of course exceedingly diminu- 

 tive ; at that period it resembles a microscopic kidney-bean, and 

 is completely destitute of legs or other external organs. After 

 a few days the embryo Julus changes its skin, and, throwing off 

 its first investment, appears divided into distinct segments, and 

 furnished with a head, a pair of simple eyes, a pair of antennae, 

 and six jointed legs attached to the anterior rings of the body 

 (fig- 99, B, c). Some days subsequent to its first moult, the 

 skin is again cast, and the millepede acquiring larger dimensions is 

 seen to possess seven pairs of ambulatory extremities, which are, 

 however, still placed only upon the anterior segments (Jig. 99, D). 

 When twenty-eight days old, they again throw off their outward 

 covering, and assume, for the first time, their adult form : they 

 then consist of twenty-two rings, and have twenty-six pairs of 

 feet ; but, of these, only the eighteen anterior pairs are used in 

 progression. At the fourth moult the number of legs is increased 

 to thirty-six pairs ; and at the fifth, at which time the body be- 

 comes composed of thirty segments, there pfg m 100. 

 are forty-three pairs of locomotive organs. 

 At last, in the adult state, the male has 

 thirty-nine and the female sixty-four rings 

 developed; but it is not until two years after 

 this period that the sexual organs appear, 

 and the animals become capable of repro- 

 duction. 



(272.) Scolopendrida. In the second 

 family of Myriapoda we have a very striking 

 illustration of the manner in which the de- 

 velopement of the nervous centres proceeds 

 step by step with that of the external limbs. 

 The slow-moving Julidse possess in their 

 rudimentary feet organs adapted to their 

 condition, and their feeble powers of locomo- 

 tion are in relation with their vegetable 

 diet and retiring habits. But in the pre- 

 daceous and carnivorous Scolopendra (Jig. 

 100), which, although it lurks in the 

 same hiding-places as the Julus, obtains 

 its food by pursuing and devouring insects, 



