CILIOBRACHIATE POLYPES; BOWERBANKIA. 531 



surrounding it. The food appears to be retained for a consider- 

 able time in the stomach, and may frequently be seen to pass 

 back into the gizzard, for the purpose of being again submitted to 

 its operations. After being subjected to the digestive process in 

 the stomach, the particles which remain are transmitted into the 

 intestine ; but previously to their entering it, they are seen to 

 rotate for some time about its orifice, the movement being pro- 

 duced by the action of the cilia that fringe it. The granular 

 matter accumulates in little pellets in the intestine; and when 

 these pass out from its extremity, they are immediately whirled 

 off to a distance, by the same action of the cilia upon the arms, 

 as that which produces a current towards the mouth. 



1103. Considerable power of selection appears to be enjoyed 

 by these Polypes in regard to their food. The movements of 

 the cilia which fringe the tentacula, seem entirely under the con- 

 trol of the individual ; and by their vibrations currents of water 

 are produced, which bring particles of various kinds of living 

 and dead matter to the entrance of the alimentary canal. It 

 has been sometimes noticed that animalcules, which have thus 

 been drawn into the pharynx, escape during the act of swallow- 

 ing ; but they are usually met by one of the tentacula, which 

 bends inwards, and by means of a sharp blow drives them back 

 into the mouth. They do not immediately perish in the stomach, 

 but may sometimes be seen to continue their movements for a 

 considerable period within its cavity. Of the vortex which is 

 drawn by the cilia towards the mouth, a considerable amount 

 passes out between the bases of the arms; and this usually 

 contains the finer particles, which thus escape. Of those which 

 remain within the cone, those of fitting size are received into the 

 pharynx ; and, when they have passed downwards to its termi- 

 nation, a more perfect selection appears to take place, by which 

 some are admitted into the stomach, whilst others are rejected. 

 Besides this regular flow of water into the pharynx, the fluid is 

 occasionally introduced in larger quantity, by the sudden dilata- 

 tion of the tube, which quickly returns to its former diameter, 

 and expels a large part of what it had thus taken in. This 

 movement is not improbably connected with the function of 



