SCOLOPENDEID^E. 



287 



Fig. 142. 



duced at the former change, from the eighth to the twelfth inclusive 

 (fig. 141, E, 8-12), are hecome of the same size as the original ones, and 

 each has developed from it two additional pairs of legs, so that the 

 whole number becomes increased to thirty-four; and thus at each 

 change of skin the number of new segments and of additional legs is 

 increased, by development from the germinal membrane, until the full 

 complement is acquired. 



(739.) SCOLOPENDEID^J. In the second 

 family of Myriapoda we have a very striking 

 illustration of the manner in which the de- 

 velopment 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 locomotion are in relation with their 

 vegetable diet and retiring habits. But in 

 the predaceous and carnivorous Scolopendra 

 (fig. 142), which, although it lurks in the 

 same hiding-places as the Julus, obtains its 

 food by pursuing and devouring insects, 

 far greater activity is indispensable; and 

 accordingly we find the segments of the 

 body, and the extremities appended to 

 them, exhibiting a perfection of structure 

 adapted to greater vivacity and more ener- 

 getic movements. 



(740.) This is at once evident upon a 

 mere inspection of their outward form : the 

 individual segments composing the animal 

 are much increased in their proportionate dimensions, and, instead of 

 being cylindrical, each division of the body is flattened and presents a 

 quadrangular outline. In order to give greater flexibility to the animal, 

 instead of the semicrustaceous hard substance which forms the rings of 

 the Julus, the integument is here composed of a tough and horny sub- 

 stance, forming two firm plates, one covering the back, the other the 

 ventral aspect of the segment, while all the lateral part is only incased 

 in a flexible coriaceous membrane, with which the individual rings are 

 likewise joined together. Such an external skeleton is obviously calcu- 

 lated to give the greatest possible freedom of motion, and thus to enable 

 the Scolopendra to wind its way with serpent-like pliancy through the 

 tortuous passages wherein it seeks its prey. 



(741.) The ventral chain of ganglia belonging to the nervous system 

 presents a series of nervous centres of dimensions proportioned to the 

 increased bulk of the segments in which they are lodged, and becomes 



Scolopendra. 



