BRYOZOA. 109 



bruised before its introduction into the proper stomach. The 

 mouth is placed in the centre of the space enclosed by the tenta- 

 cula ; it appears to be a simple orifice, incapable of much distension, 

 through which the particles of food brought by the ciliary action 

 pass into a capacious oesophagus, (Jig- 45, a, 1, 2,) which, gradually 

 contracting its dimensions, ends in a globular muscular organ to 

 which the name of gizzard has been applied. (8) The walls of this 

 viscus are composed of fibres which radiate from two dark points 

 seen in the figure, and its lining membrane is covered with a great 

 number of hard horny teeth, so disposed as to represent, under the 

 microscope, a tesselated pavement. The contractions of the giz- 

 zard are vigorous ; and, from the structure of its interior, its office 

 cannot be doubtful. 



To the gizzard succeeds a stomach (j^^.45, #, 4,) which is studded 

 with brown specks apparently of a glandular nature, and probably 

 representing a biliary apparatus. The intestine leaves the stomach 

 at its upper portion, close to the gizzard (5) ; and, running parallel 

 with the oesophagus towards the tentacula (6), terminates at the side 

 of the mouth (7), in such a position that excrementitious matter is at 

 once whirled away by the ciliary currents. The whole intestinal 

 apparatus floats freely in a visceral cavity, which contains a transpa- 

 rent fluid, and encloses distinct muscular fasciculi, which we shall 

 speak of in another place. 



The process of digestion in this minute, yet highly organized being, 

 is well described by Dr. Farre in the memoir above mentioned. 



" The little animal, when in vigour, is seen projecting from its cell 

 with the arms extended, and the cilia in full operation ; the upper 

 part of the body being frequently turned from side to side over the 

 edge of the cell, the extremity of which, from its peculiar flexibility, 

 moves along with it. The particles carried to the mouth in the 

 vortex produced by the action of the cilia, after remaining a little 

 while in the pharynx, are swallowed by a vigorous contraction of 

 its parietes, and carried rapidly down the oesophagus and through 

 the cardia to the gizzard, which expands to receive them. Here 

 they are submitted to a sort of crushing operation, the parietes of 

 the organ contracting firmly upon them, and the two dark bodies 

 being brought into opposition. Their residence, however, in this 

 cavity, is only momentary, and they are immediately propelled into 

 the true stomach below, where they become mixed up with its 

 contents, which, during digestion, are always of a dark, rich, brown 

 colour, being tinged with the secretion of its parietal follicles." 



