518 ORESSWELL SHEARER. 



It not only adds a very primitive Annelid form to the already 

 large class of animals possessing uepliridia of this primitive 

 type, but the presence of soleuocytes on all four or five 

 pairs of nephridia in Dinophilus shows, I think, that in 

 the primitive Annelids not only the head-kidney and the 

 immediately following segments, as in Polygordius, were 

 furnished with solenocytes, but the nephridia of all the 

 segments ; and that while in some Annelids they have been 

 retained on the nephridia of most of the segments, others 

 have lost them or retained them only on the nephridia of the 

 anterior segments. Moreover, the presence of solenocytes in 

 Dinophilus is of interest on account of the many relation- 

 ships this group shows with that of the Platyhelminths. 

 Weldon (24) has pointed out the similarity of the muscular 

 oesophageal appendage of Dinophilus to the pharynx 

 of Planarians, and Harmer (8) has already called atten- 

 tion to the median position of the generative pore and 

 the method of fertilisation of the male D. t^eniatus as 

 showing a certain affinity to Platyhelminths. The crawling 

 swimming movements of Dinophilus and its manner of 

 feeding is also suggestive of some relationship to this group. 

 As will be seen from consulting figs. 12, 13, and 15 of the 

 present paper the ventral surface of Dinophilus is defi- 

 nitely thickened into a crawling pad as in the Turbellaria. 



The resemblance of the nephridial canals of Dinophilus 

 to the excretory canal of the flame-cells of Thysanozoou 

 is unmistakable ; with the exception that one is furnished 

 with solenocytes and the other is not, there is little difference 

 between the two. The granular walls of the organ gradu- 

 ating into a delicate tube-like canal is found in each, and 

 their whole appearance is remarkably the same in both cases. 

 From this resemblance I think it is not impossible to look 

 for the discovery of solenocytes in some of the higher Platy- 

 helminths. Their discover}' in this class will then definitely 

 establish the homology of Platyhelminth protonephridia with 

 the solenocyte-bearing nephridia of Annelids and the kid- 

 neys of Amphioxus. It may then be possible to trace a 



