SOME POINTS IN THE STRUCTURE 



OF THE LARVA OF LANICE CONCHILEGA 



INTRODUCTION. 



The'tubicolous polychsete worm Lanice conchilega, during its early 

 development passes through a larval stage which like ail the larvae of the 

 group, is pelagic in habit. Thèse pelagic larvae présent however the remar- 

 kable character of being enclosed very early in a thin transparent tube. 

 They are a very common constituent of the plankton collected with the 

 townet along the Belgian coast and may be found in quantity in the vici- 

 nity of ail sandy coasts and even in the central part of the North sea. 



Although this larva has been known for a considérable time, doubt was 

 thrown on its identity by Giard (1878). 



For reasons which will be mentioned presently, Giard considered this 

 form to be an entirely new species of polychsete and named it Wartelia 

 gonotheca. 



More recently Nordenskiold (1901) has given an incomplète descrip- 

 tion of this larva under the title of Wartelia gonotheca, without however 

 entirely endorsing Giards opinion, that it is a distinct species. 



The earliest account of this larva is that given by Claparede (1863), 

 who described it very fully at various stages of development, the descrip- 

 tion and drawings are however limited to external characters. 



CuNNiNGHAM and Ramage (1888) also give a short description and a 

 drawing of the larva. 



Our own observations agrée in the main with thèse descriptions, and 



