58. 



s. GOTO. 



Tlie oesoplingus leads into the intestine. This always consists of 

 two branches, which proceed towards the posterior end of the 

 body, wliere they unite together in some species, or in others 

 remain separate. They traverse the body midway between the 

 dors:d and the ventral side, and divide it lengtliwise into three, 

 roughly equal areas, in the central one of which is placed the greater 

 part of the genital organs, while in the lateral areas only the vitel- 

 larium is generally present. The two divisions of the intestine send 

 out lateral branches on both sides ; but those of the inner side are 

 generally very short, Avhile those of the outer are long and bifurcate 

 reneatediv before reachin2: tlie lateral Ijordcrs of the body. In some 

 a"-ain, as in Ilexacotijle (PI. XIIT), there are, besides the two main 

 branches of the intestine above mentioned, two others which are 

 situated close to the lateral borders of the body, and extend backwards 

 through the anterior two-thirds of the body. In this genus as well 

 as in ]\Ucr. reticulata, the branches of the intestine form a close 

 net-work not only in the lateral l)ut also in the medi:ni portion of 

 the body. The relative arrangements of the main divisions of the 

 intestine as well as of their branches will however be best gathered 

 from the accompanying plates and the description of species, so that I 

 may here pass them over, and proceed to the consideration of the 

 intestinal epithelium. 



Two types of intestine may be distinguished according to the 

 character of the cells that constitute its epithelium. In the first type, 

 the cavity of the intestine is destitute of any continuous epithelium, 

 but is bounded directly by a tunica propria, on the surface of which 

 lie cells without any membrane, which contain in their protoplasm 

 numerous, yelhjwish, d:u-k-brown, or almost black granules of strong 

 refractive power. In luost species, there is a distinct nucleus, and in 

 some, as in Ondwcotijlc spinacis (PI. XV, figs. 7 and 10), also a well 



