574 MAYNAKD M. METO ALF, 



into a thicker-walled portion of the alimentary canal, which (except 

 for some peculiarities soon to be pointed out) it would be natural to 

 call the oesophagus. This soon widens into a large chamber, the 

 stomach, with its internal surface longitudinally plicated, the folds 

 being large and prominent. The intestine shows the loop characteristic 

 of so many Tunicates, the rectum bending to the left of the stomach 

 to open into the large atrial chamber which surrounds the visceral 

 mass. In my very poorly preserved material I am unable to de- 

 monstrate any liver or intestinal gland. I do not think that either 

 was present in the living individuals, but they may have been present, 

 though now broken down as a result of the maceration to which the 

 specimens were evidently subjected before preservation. The endo- 

 thelium of the alimentary canal is destroyed, for the most part, and, 

 as these glands, if present, would have consisted chiefly of epithelial 

 cells, they also may have been destroyed, while the tougher, meso- 

 dermal part of the walls of the alimentary tube proper has been 

 preserved. The numerous patches of endothelial cells left on the inner 

 surface of the "oesophagus", stomach and intestine show the cells to 

 be cubical or columnar and arranged in a single layer. The large 

 folds or plications of the inner wall of the stomach, and the smaller 

 and less definitely arranged folds of the inner surface of the "oeso- 

 phagus" and intestine, are not mere folds in the epithelium, but each 

 fold has an axis of connective tissue, covered by the reflected epi- 

 thelium. 



The structure, which, at first glance, seems to be the oesophagus, 

 deserves a little more careful scrutiny. Its upper end is really a 

 modified part of the pharynx, as is indicated by the presence of 

 several typical pharyngeal organs. On its (morphologically) ventral 

 surface a very short endostyle is present. In 0. hithyus the endo- 

 style lies, in part at least, on the floor of the enlarged upper portion 

 of the pharynx. In my specimens I find in the latter position no trace of 

 endostyle. The peripharyngeal bands I have not found. The dorsal lamina 

 is present as a fold pushing into the lumen of the tube from the dorsal 

 side. The free edge of the fold bears a groove lined by columnar 

 cells. On the free border of these cells is a line of very fine granules 

 which seem to be the remains of cilia. It is not possible, however, 

 in such poorly preserved material, to be sure of this point. The 

 dorsal lamina is short, soon sinking, posteriorly, to the level of the 

 general inner surface of the digestive tube, and, at the same time, 

 losing the faint indication of cilia. In front of the dorsal lamina, and 



