480 K. lUMUNNl MENON. 



(3) Notocliords. — In the alimentary canal of Actino- 

 trocha, Masterman describes an oesophagus, a collar stomach 

 or pharynX; an oesophagus leading from this into the true 

 stomach, and an intestine. I have been able to make out 

 only three divisions in the alimentary canal — a tube leading 

 from the mouth to the stomach, which obviously corresponds 

 to the oesophagus (Masterman), a stomach placed partly in 

 the collar and partly in the trunk segments, and an intestine. 

 It seems to me that this oesophagus corresponds to the 

 stomodseum, pharynx, and oesophagus of Cephalodiscus, 

 described by the same author. However this may be, the 

 '^ oesophagus " is often folded transversely (this is also the 

 case in young Phoronis) into pouches, and the subneural 

 gland is a diverticulum of its dorsal Avail. The "oesophagus " 

 opens into the large stomach anteriorly and dorsally. The 

 anterior part of the stomach grows forwards in the form of 

 a diverticulum, which is placed ventrally to the oesophagus. 

 This diverticulum is absent in the young forms. The 

 anterior end of the diverticulum may be bilobed, and the 

 two lobes, often unequally developed, lie ventro-laterally or 

 laterally to the oesophagus. There can be no doubt that the 

 diverticulum with the lobes is the sti'ucture referred to as 

 "the notochord,'^ "hepatic diverticula," etc., although it 

 must be confessed that I have not seen vacuoles or brown 

 concretions, stated to occur in these structures. Indeed, I 

 have not been able to inake out any difference between the 

 lining membrane of the diverticulum and that of the rest of 

 the stomach. The cells are columnar ciliated cells, and are 

 taller than the cells of the " oesophagus," and the nuclei 

 form an irregular layer between the base and the middle of 

 the cells. The protoplasm of the cells presents a granular 

 appearance and stains homogeneously, but not so deeply as 

 the protoplasm of the oesophageal cells, and does not differ in 

 any respect from the protoplasm of the lateral ridges of the 

 stomach. These ridges of protoplasm, containing numerous 

 scattered nuclei and large vacuoles Avith remnants of food 

 particles in them, ai"e two longitudinal ridges projecting i^ito 



