ACTINOZOA. 219 



the Beroidce, and the Stenostomata^ including all 

 remaining members of the order. 



The apical area, also, presents its own peculiar 

 variations. In general it appears as a somewhat 

 oblong flattened space, bounded by a distinct 

 ridge, its long diameter coinciding with that of 

 the mouth. The ridge is usually smooth, and the 

 general surface of the included region covered 

 with very fine cilia. But in the Beroidce a num- 

 ber of conspicuous, though short, arborescent fila- 

 ments fringe the margin of the area, which, in this 

 family, appears divided into a pair of shallow, ovate 

 lobes, converging to a point at the apical pole of 

 the body. 



The modifications of the nutrient system now 

 require our attention. The whole of this appa- 

 ratus may, for purposes of description, be resolved 

 into the following minor systems or groups of 

 parts : — 



1. An axial system; including the digestive tube, 



the funnel, and the apical canals. 



2. A paraxial system. To this belong the para- 



gastric canals arising from the funnel, and an 

 oral vessel, or vessels, into which, in some 

 genera, their distal extremities open. 



3. A ctenophoral system ; the eight canals of 



which may be variously prolonged to supply 

 the lobes or other appendages of the body ; 

 and — 



4. A radial system ; or those channels whereby 



the several elements of the preceding system 

 become connected with the funnel. 



I. The parts of the axial system vary but little 

 throughout the order. In Pleurohrachia the di- 



