OXFORD UNIVERSITY SPITSBERGEN EXPEDITION. 



1131 



body-wall. Extreme degeneration may exist throughout the 

 whole of the alimentary tract behind the septal glands. 



This condition might be due to the presence of parasites — there 

 are a num.ber of such, elongated, cylindrical, with a nucleus of 

 corresponding shape, in the oesophagus (probably Ciliates, though 

 no cilia could be made out on them), as well as a number of small 

 cysts in the tissues. Still, the usual Ciliate parasites of the 

 oesophagus of Enchytrseids do not as a rule cause such degenera- 

 tion. It might perhaps be due to the parasites of the tissues, 

 through their metabolic products, which may have a specific 

 action on the alimentary epithelium. Or one might attribute it 

 to the food (assuming that the worms Avere taking in material 

 from the body of the dead seal in which they were found), but for 

 the fact that the last species also showed degeneration of the 

 alimentary epithelium, though not to such an extreme degree as 

 these worms. 



Text-figure 4. 



Cerebral ganglion of Ltmihricilhis necrophagus. 



A lightly staining, almost perfectly homogeneous, very slightly 

 granular coagulum, containing many nuclei, almost fills up the 

 ccelom in the anterior part of the body. There are no definite 

 lymph-corpuscles of the type of those found in the former species ; 

 but the nuclei in the coagulum just described seem to have 

 belonged to corpuscles which have degenerated. These changes 

 seem to go along with those in the intestine, and are doubtless 

 due to the same cause. 



The dorsal vessel begins in segm. xiv. The blood contained 

 hsemoglobin. 



The anteseptal part of the nephridia is quite small and 

 shortly cylindrical. The postseptal portion is elongated and is 

 continued behind into the duct, which has the same structure 

 as in the last species. The whole is fiattened against the body- 

 Avall. 



The cerebral ganglion is rectangular in general outline (text- 

 fig. 4), the sides being approximately parallel and the length 



