RELATION OF THE NEMEBTEA TO THE VERTEBRATA. 605 



The Relation of the Nemertea to the 

 Vertebrata. 



By 



A. A. W. Hulbreclit, 



Professor iu Utrecht. 



With Plate XLII. 



In venturing at the close of my Report on the Nemertea, 

 collected by H.M.S. " Challenger/^ to leave the region of 

 demonstrated facts and actual observations, and to enter upon 

 that of speculation and suggestion, I gladly availed myself of 

 the permission for so doing granted to me by the editor, Mr. 

 John Murray. I thought it necessary to ask for that permis- 

 sion, because general speculations on the ancestry of the 

 Chordata hardly appeared to me to fit into the framework of 

 those Reports. My desire in this case to deviate from a rule 

 which I held to be salutary, was due to the fact that of late 

 these speculations have been conducted along very varying 

 channels, an entirely new one having only very lately been 

 opened by Bateson^s important series of papers on Balano- 

 glossus. An attempt to give more depth to one of these 

 channels, and thus to lead into it the attention of a greater 

 number of my fellow-workers, especially commended itself to 

 me, since it was my conviction that the lines laid down by 

 myself in former publications derived considerable support 

 from the " Challenger " material, and were thus entitled to a 

 renewed and full consideration. 



• Published by permissioa of the editor of the ' Zoology of the Challenger 

 Expedition,' Mr. John Murray, F.R.S.E, 



