THE RELATIONSHIPS OF THE SEA-SPIDERS. 16/ 



and the Pantopod-larva of the Pycnogonids. And 

 although on this supposition we might suppose so 

 great a transitional change as Dohrn believes to have 

 taken place, yet it also carries with it the assumption 

 that a new larval form may have been acquired with 

 ease within such a group independently of any previous 

 (ancestral) stages. Hence we are left in an unpreju- 

 diced position to choose between these two possibilities! 

 And for my own part I am led to the conclusion, from 

 the foregoing facts of development, that the Pantopod- 

 larva is neither a primary form, as Hoek supposes, nor 

 represents a much modified Trochophore, as held by 

 Dohrn. And it seems to me far simpler and much 

 more in accordance with the facts to believe that we 

 have here a clear case of a secondary larval-form. 



