384 MR. LISTER ON THE STRUCTURE AND FUNCTIONS 



were noticed, the seeming revolution of the teeth was upwards on the right, and 

 downwards on the left of each arm when viewed at the back ; and several times a 

 small globule of food lodged on an arm and travelled down it to the mouth, while 

 the arm remained expanded and the cilise in full play. 



From the back of the arms in most species a few fine pointed hairs were seen pro- 

 jecting singly or in pairs, and nearly at a right angle, as if to give notice of any- 

 thing coming within their touch. What appear strong muscles, characterized by 

 cross hatchings, run longitudinally from the insertion of the arms downwards. 

 Within these, in the mouth, food commonly collects, and has a revolving motion 

 there till swallowed or sometimes rejected. The act of swallowing is distinct and 

 energetic. Plate XII. fig. 2 represents one of the animals of Flustra pilosa, both closed 

 and expanded ; from a specimen that rose like a small leaf from the fucus it encrusted: 

 and fig. 3 gives those of F. papyracea when drawn in. Both species, in the latter 

 position, have the arms, c 2, lying lengthwise and extending to the valve h, the 

 mouth in the same line, and the neck folded back. At its other end the neck is joined 

 to the side of a sort of pouch, which is indistinctly spotted, and of a reddish ochreous 

 colour, closed at the bottom, and with a small circumscribed space in front con- 

 taining particles in constant revolution, their motion having the same axis as the 

 vessel : continuing forwards from this part, it becomes greatly contracted, and then 

 assumes a sudden enlargement, generally filled with opake matter. The mouth and 

 neck are placed indifferently on either side of the other parts. The whole animal 

 of each species is moveable within the cell, and filaments are seen attaching it to the 

 bottom and sides. 



When the arms and mouth of Flustra pilosa were protruded, a vacancy was left 

 in the sheath V on one side ; the neck was drawn forwards into the same line as the 

 mouth ; the enlarged end of the vessel in front of the pouch was also carried forwards, 

 and its opake contents were in several instances expelled in pellets through the open- 

 ing at the side of the sheath, and then again accumulated ; proving this to be the 

 anal orifice. 



The course of the food swallowed was not made out beyond the neck, nor were 

 the viscera which the pouch might contain. It seems analogous to the part marked 

 by Savigny as ovaries in several figures of his excellent work on Jscidice, but from 

 its position we may be allowed to suppose, that at least a stomach and liver have a 

 place in it. 



Between the animals of Cellularice and those of Flustrce, no line of distinction was 

 detected, though the number of arms and other details vary according to the species. 

 In most that were inspected, the cells from their position or opacity did not allow a 

 sight of the interior ; but the general strong resemblance of the parts exposed led to 

 the inference that a structure like that described, with a separate termination of the 

 intestine, extended throughout. 



This was plainly observable in Serialaria lendigera, a common species, with eight 



