MYRIAPODA. 



subsistence by devouring decomposing animal and vegetable sub- 

 stances. The body is long and cylindrical, composed of between 

 forty and fifty hard and brittle rings, which, with the exception of 

 those forming the head and tail, differ but slightly from each other. 

 Every segment supports two pairs of minute feet, arising close to 

 the mesian line upon the under or ventral surface ; but these feet, 

 although distinctly articulated {fig- 98, c), are as yet extremely 

 small in comparison with the bulk of the animal, and are evidently 

 but mere rudiments of the jointed legs developed in more highly 

 organized forms of homogangliate beings ; so that the movements 

 of the Julus are very slow, and the creature seems rather to glide 

 along the ground, supported on its numerous but almost invisible 

 legs, than to walk. When at rest, the body is rolled up in a 

 spiral form (j%. 98, B), the feet being concealed in the con- 

 cavity of the spire, and thus protected from injury. 



(269.) The mouth resembles in structure that of the larva of 

 some insects, and is furnished with a pair of stout horny jaws, mov- 

 ing horizontally, and provided at their cutting edges with sharp den- 

 ticulations, so as to render them effective instruments in dividing 

 the fibres of rotten wood, or the roots and leaves of vegetables, 

 which are usually employed as food ; and the alimentary canal, 

 which is straight and very capacious, is generally found filled with 

 materials of this description. 



(270.) In most points of their internal organization, the Myria- 

 poda resemble insects ; and we should only anticipate the obser- 

 vations which will be more conveniently made hereafter, did we 

 enter into any minute description of their anatomy : we shall, there- 

 fore, in this place, simply confine ourselves to the notice of those pe- 

 culiarities which occur in the animals under consideration, by which 

 they are distinguished from insects, and entitled to rank as a dis- 

 tinct class. We have seen that in such of the Annelida as have 

 been most carefully investigated, the orifices of the sexual organs 

 are situated near the anterior part of the body, not, as is invariably 

 the case among insects, at the caudal extremity : in this particular 

 the JulidfE still present analogies with the red-blooded worms ; 

 for in them the external openings of the male parts are situated im- 

 mediately behind the base of the seventh pair of legs, and are found 

 to be placed upon minute mammillary protuberances, which are 

 each furnished with a sort of hooked scale, adapted to hold the 

 female during the process of impregnation. 



In the female, also, the sexual orifices are advanced very far 



