Cyathocormus mirabilis n. g., n. sp. 21 



of simple flat cells. The undulations of this epithelium shown in 

 the figure are, I l>elieve, due to contraction incident to preserva- 

 tion. 



Aliiucntarij canal. The alimentary canal is contained partly in 

 the thorax and partly in the abdomen. Excluding the branchial 

 sac, which is the foremost portion of the canal, it may be divided 

 into three parts, the oesophagus, the stomach, and the intestine 

 (PL III., fig. 15). 



The oesophageal opening is placed at the posterior end of the 

 branchial sac, nearer the dorsal than the ventral edge (PI. IL, fig. 

 8, oe.). It is separated from the hind end of the endostyle by a 

 narrow space where the bottom of the branchial sac is lined with 

 thin epithelium. As shown in the figure, the terminal portion of 

 intestine lies immdiately beneath this part in close contact with 

 the oesophagus. The oesophagus is rather short and funnel-shaped, 

 with the wajl thrown into irregular longitudinal folds (PL III., fig. 

 15). Generally the course of the oesophagus is a little curved. 

 The anterior margin of its wall is somewhat raised and forms a 

 distinct ridge or lip (PL III., fig. 18). Posteriorly the oesophagus 

 projects into the cavity of the stomach considerably and seems to 

 perform the function of a valve (PL III., fig. 16). The wall of 

 the oesophagus is lined with columnar epithelium and is finely 

 ciliated all over. In sections stained with haemalaun the zone 

 formed by inner halves of these cells is coloured dark blue and 

 stands out very conspicuously. In the part projecting into the 

 interior of the stomach the cells do not show any such differen- 

 tiation. 



The stomach is oval-shaped with smooth and uniformly 

 thick Avail. The anterior end of the organ is rounded with an 

 invagination at the centre, forming a sheath for the oesophagus 

 which proceeds a short distance into the interior (PL III., fig. 16). 

 The posterior end, on the contrary, terminates quite abruptly and 

 without any constriction. The stomach, therefore, is comparable 

 in form with an egg from which the posterior third (next the 

 pointed end) has been cut away. The wall is of considerable 

 thickness being lined with an epithelium of tall columnar cells. 



