244 FEANK E. BEDDARD. 



complicated as to present the appearance of a bundle of 

 longitudinally running vessels. 



In Hy periodrilus the ventral oesophageal pouches are in 

 certain respects more remarkable. There are three of them in 

 Segments 9, 10, and 11 — one pouch to each segment. 



The pouch appears to communicate with the oesophagus a 

 little to the right of the ventral median line. The orifice is 

 narrow, and the cells are at first identical with those which 

 constitute the epithelial lining of the oesophagus ; the cells 

 are tall and columnar, and between their bases are spherical 

 or pear-shaped darkly staining cells (fig. 31) like those of 

 the oesophagus. Tracing the pouch back, the cells are seen 

 to alter their character, and to become low and quadrangular 

 in form, while the epithelium is so folded as to give the appear- 

 ance of a series of tubes running approximately parallel to 

 each other (fig. 25). At the point of origin of the pouch, as 

 shown in fig. 31, the muscular wall of the oesophagus and the 

 peritoneal covering becomes reflected over the gland in such a 

 way as to leave a wide space between itself and the pouch; 

 further back this space is obliterated by the coalescence of the 

 muscular and peritoneal layers with the outer layer of the gland. 



Further from the point of the opening of the gland into the 

 intestine the appearance of parallel running tubes is increased, 

 and they have become at the same time of smaller calibre. 

 The cells which form the lining epithelium are broad and 

 somewhat flat, though quadrangular in form ; the nuclei are 

 thus, owing to the large size of the individual cells, very far 

 apart, and the cell outlines are not distinguishable. As the 

 folding gets more and more complicated the " tubes " present 

 more and more the appearance of having an intra-cellular 

 lumen; this actually does take place at the extremity of the 

 pouch. One of the last sections through a pouch is illustrated 

 in fig. 26 : it will be seen there that three comparatively wide 

 tubules end in a complicated meshwork of fine capillary tubes; 

 the section presents the strongest possible resemblance to a 

 portion of a uephridial network such as I have figured in 

 Acanthodrilus multiporus. Even the three large tubes 



