272 



ORDER IX. COPEPODA. 



810. The Entomostraca of this Order bear a strong resem- 

 blance in the general form of their bodies to the Edriophthalma ; 

 they have no carapace, nor bivalve shell, like that of the last 

 Order ; and their envelope is of membranous or soft consistence. 

 The head is large, and distinct from the thorax ; and the body is 

 distinctly divided into several segments, of which the thorax pre- 

 sents from three to five, and the abdomen two or more. The num- 

 ber of legs is always at least eight or ten ; and the abdomen is ter- 

 minated by a bifid tail adapted for swimming. The first pair of 

 antenna is long, slender, and many-jointed ; those of the second 

 pair are sometimes wanting, and sometimes developed into swim- 

 ming-legs. The mouth is furnished, besides the mandibles and 

 maxillse, with two or three pairs of feet-jaws ; of which the pos- 

 terior are usually very large, and furnished with a set of feathery 

 bristles, which almost cover the remainder of the buccal appa- 

 ratus. In one division of the Order, we find the two eyes quite 

 distinct ; in the other they form but a single mass on the median 

 line. The eggs are contained, when they quit the ovarium, in 

 two capsules borne at the base of the tail (Fig. 489) ; and the 

 young, when they first emerge from them, present a form differ- 

 ing greatly from that of the parent, which is only attained 

 after several moults (Figs. 496, 497). The Cyclops is a very 

 common genus of this Order ; belonging, as its name implies, to 



FIG. 496 LARVA OF THE CYCLOPS. FJO. 497. CYCLOPS. 



the single-eyed division of it. This genus contains numerous 

 species ; of which some belong to fresh water, whilst others are 



