224 



CHAPTER XIV. 



MYRIAPODA.* 



(266.) The Annelidans examined in the preceding chapter, with 

 the singular exception of the earthworm, are only adapted to an aqua- 

 tic life ; the soft integument which forms their external skeleton and 

 the setiform and tentacular organs appended to the numerous seg- 

 ments of their elongated bodies, are far too feeble to support them 

 in a less dense and buoyant element, so that when removed from 

 their native waters they are utterly helpless and impotent. Sup- 

 posing, however, that, as a mere matter of speculation, it was in- 

 quired by what means animals of similar form could be rendered 

 capable of assuming a terrestrial existence, so as to seek and obtain 

 prey upon the surface of the earth, and thus represent upon land 

 the Annelidans of the ocean : a little reflection would at once in- 

 dicate the grosser changes required for the attainment of such an 

 object. To convert the water-breathing organs of the aquatic 

 worms into an apparatus adapted to aerial respiration would be the 

 first requisite. The second would be to give greater density and 

 firmness to the tegumentary skeleton, to allow of more power- 

 ful and accurately applied muscular force, by diminishing the num- 

 ber of segments composing the annulose covering, and also by 

 converting the lateral oars into jointed levers of support sufficiently 

 strong to sustain the weight of the whole body, to provide instru- 

 ments of locomotion fitted for progression upon the ground. Yet 

 all these changes would be inefficient without corresponding modi- 

 fications in the character of the nervous system : the lengthened 

 chain of small ganglia found in the aquatic worms would be quite 

 inadequate to wield muscles of strength adapted to such altered cir- 

 cumstances ; the small encephalic brain would be incompetent to 

 correspond with more exalted senses, so that, as a necessary conse- 

 quence of superior organization, the nervous centres must be all 

 increased in their proportionate developement to adapt them to 

 higher functions. 



The changes, which our supposition infers would be requisite 

 for the conversion of an aquatic Annelidan into a land animal, are 

 precisely those which we encounter when we turn our attention 

 from the creatures described in the last chapter to the MYRIA- 

 PODA, upon the consideration of which we are now entering : . 



* (*,v(>ux.S) ten thousand, i.e. many ; vrovs, a foot. 



