282 MYBIAPODA. 



evidently but mere rudiments of the jointed legs developed in more 

 highly organized forms of homogangliate beings ; the movements of the 

 Julus are, consequently, 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 

 (fig. 139, B), the feet being concealed in the concavity of the spire, and 

 thus protected from injury. 



(724.) The mouth resembles in structure that of the larvae of some 

 insects, and is furnished with a pair of stout horny jaws, moving hori- 

 zontally, and provided at their cutting edges with sharp denticulations, 

 so as to render them effective instruments in dividing the fibres of rotten 

 wood, or the roots and leaves of vegetable substances usually employed 

 as food ; and the alimentary canal, which is straight and very capacious, 

 is generally found filled with materials of this description. 



(725.) In most points of their internal organization, the Myriapoda 

 resemble insects ; and we should only anticipate the observations that 

 will be more conveniently made hereafter did we enter into any minute 

 description of their anatomy : we shall therefore, in this place, simply 

 confine ourselves to the notice of those peculiarities observable in the 

 animals under consideration whereby they are distinguished from in- 

 sects and entitled to rank as a distinct class. We have seen that, in 

 such of the Annelida as have been most carefully investigated, the ori- 

 fices 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 Julidce still present analogies with the red-blooded 

 worms ; for in them the external openings of the male parts are situ- 

 ated immediately 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. 



(726.) In the female also, the sexual orifices are advanced very far 

 forward, being situated in the vicinity of the head, between the first 

 and second segments ; the sexes, however, as in insects, are perfectly 

 distinct, and the conformation of the internal organs coincides with that 

 type of structure which is common to the insect orders. 



(727.) The male generative organs of Julus are two elongated and 

 partially convoluted tubes, placed side by side beneath the alimentary 

 canal. The excretory ducts, or terminations of these tubes, run towards 

 the anterior part of the body, where they terminate in two minute in- 

 tromittent organs, situated at the under surface of the seventh segment, 

 immediately behind the seventh pair of legs. As they pass backwards, 

 the secerning tubes, or testes, gradually separate from each other, and 

 have developed from their sides, at short distances from each other, 

 numerous small glandular caeca, which doubtless constitute the se- 

 creting portions of the apparatus, or proper testes. The two efferent 



