230 CTENOPIIOR^. Part II. 



rather wide tubes arising from the main trunks of the central chymiferous cavity, 

 and following the middle of the lateral surface of the compressed digestive sac in 

 a vertical course up to the margin of the mouth, as Fig. 21 r r shows. Toward 

 the abactinal pole, however, the main cavity extends in the form of a funnel, and 

 terminates with two holes near the centre of the circumscriljed area. This funnel 

 lies vertically in the centre of the animal, and extends therefore in its central axis. 

 It assumes nearly the same appearance in whatever position it is seen, excepting 

 only its ahactinal termination, which is furcate when seen from the side, as in 

 Fig. 22 p /-, and simple when seen in front, as in Fig. 23 p. This part of the 

 cavity with its main lateral trunks being, as it were, the centre of the circulation, 

 we may view it as a hollow axis branching right and left, and extending along the 

 centre in two parallel forks, one on each side of the digestive cavity, as far as the 

 mouth ; so that, when examined from the side, only one of the two actinal forks is 

 visible liehind the tentacvdar socket, while the short aljactinal forks, which are at 

 right angles with the former, are Ijoth distinctly seen, and vice versa. The main 

 lateral stems and their ramifications present their broad side in the last j^osition, 

 and appear foreshortened in the other. 



The two main lateral trunks {Fig. 23 e e) branch off at right angles from the 

 central cavity, and extend sideways and for some distance horizontally, with a slight 

 inclination towards the actinal pole, changing however their position to some extent, 

 according to the state of contraction or distension of the digestive cavity. Six 

 branches, or rather three, if we take their closer connection into account, arise on 

 each side from these main trunks, besides those which are close to the digestive 

 cavity. The fact is, that after giving off the cadiac tubes and before branching 

 again, the two main trunks form, at their extremity, sideways, a sort of dilatation, 

 from which arise two lateral branches extending horizontally backward and forward, 

 and two others close together which extend in a vertical direction. The Ijranches 

 extending horizontally forward and backward give out, not ftxr from their origin, 

 two other branches, which also extend horizontally, but bend sideways, nearly at 

 right angles with the former. All these branches originate so near the point where 

 they communicate with the primitive main trunks, that they might, with almost 

 equal propriety, be considered as arising directly from it. The termination of the 

 main trunk may, indeed, contract or dilate in such a manner as to appear alternately 

 divided into three, four, five, or six branches. In its most contracted state, for 

 instance, when seen from the actinal pole, as in Fig. 21, there are distinctly six 

 branches visible, arising from the main horizontal trunk, the two vertical ones 

 appearing like very short tubes, because their whole length is foreshortened upon 

 their origin, though they are actually as long as the others, whde the four horizontal 

 branches are seen for their whole extent, — two and two however, united by their 



