G Proceedings of the Royal Society of Victoria. 



their movement, while the remainder go on. If we imagine 

 the inner face of the tentacle to be anterior and the outer 

 posterior, the cilia are seen always to move upwards on the 

 right hand side and downwards on the left. 



Although I have not succeeded in observing the cilia in 

 my mounted preparations, yet we may with safety conclude 

 that they are definitely related to the two longitudinal rows 

 of columnar cells just described, and that each of these cells 

 bears a single cilium as represented in Fig. 7. 



The alimentary canal is very complex, and we can dis- 

 tinguish no less than five perfectly distinct regions, viz., 

 liharynx, aisopliagus, gizzard, stomach, and intestine. 



The mouth, as already observed, is excentrically placed 

 within the circle of tentacles (Fig. 6, o.) It leads directly 

 into a dilated pharynx lined by columnar cells (Fig. 12, x>h.) 

 The inner surface of the pharynx, i.e., that turned towards 

 the stomach, is more strongly curved than the outer surface, 

 and the constriction at the lower end of the pharynx, which 

 separates it from the oesophagus, is formed chiefly by a deep 

 inward fold of the inner surface. A sharp re-entrant angle 

 is thus formed, and over this angle the columnar epithelium 

 is higher than elsewhere. 



The oesophagus (Fig. 12, (e.) is a simple, thin- walled, 

 saccular organ, inter]30sed between the pharynx and the 

 gizzard. 



The gizzard (Fig. 1 2, giz) is certainly the most remarkable 

 portion of the whole alimentary canal. It is globular in 

 shape and has thick muscular walls, consisting mainly of a 

 stout circular band of muscles (Fig. 8, c. m. h. ; Fig. 12, 

 c. on. h), oval in section and composed of a great number 

 of delicate fibres, surr-ounding two relatively large chitinous 

 teeth {t.) The teeth are squarish in shape, and flattened. 

 They are planted within the muscular mass in such a 

 manner that their broad surfaces lie parallel with the plane 

 of the loop of the alimentary canal. This arrangement will 

 be best understood by reference to Figs. 8 and 12. 



The gizzard opens directly into the side of a very large, 

 elongated, saccular stomach, of the shape sliown in Figs. 9 

 and 12. The stomach is differentiated by the character of 

 its lining membrane into two totally distinct regions — an 

 upper, non-digestive, and a lower, digestive portion. The 

 upper portion, next to the intestine, is lined, like the pharynx, 

 by columnar epithelium, and the cells of this epithelium are 

 ciliated (Fig. 9, c. e., cil.) At about the upper level of the 



