ACTINOZOA. 221 



the general surface of the body, soon joins the 

 extremity of the oral tube of that side, before 

 gaining wliich it sends off a branch, destined, 

 after having pursued a long and devious track, to 

 anastomose with its fellow from the opposite side 

 of the body, and the complex system formed by 

 the much convoluted and prolonged extremities of 

 the intervening pair of antero-posterior canals. 

 These last, after quitting their ctenophores, which 

 are relatively much longer than those of the sides 

 of the body, are produced to supply the two large 

 lobes, in front of and behind the mouth, within 

 the substance of which, after many sinuous turns, 

 they finally blend and become lost. 



The course of the ctenophoral canals is usually 

 simple. In Chiajea Palermitana each gives off 

 on either side a number of very short straight 

 branches, which in the Beroidce are replaced by 

 somew^hat larger, arborescent tufts. 



4. Lastly, the apical extremities of the cteno- 

 phoral canals, and the manner of their communi- 

 cation with the axial system, or, in other words, 

 the disposition of the radial vessels, remain to be 

 noticed. 



In PleuTobrachia, as has been shown, the 

 primary, secondary, and tertiary radial canals 

 are very well marked, meeting the cteuophoral 

 vessels at right angles to, and about midway in, 

 their course. The apical extremities of the latter 

 are distinctly prolonged, to end csecally around the 

 oblong, flattened area. 



In the Beroidce a radial system can scarcely 

 be said to occur, the apical ends of the cteno- 

 phoral canals curving gently round, to open into 



