ON THE EMBRYOLOGY OF THE ECTOPROCTA 



BY 



SIDNEY F. HARMER, M.A., B.Sc, 



Fellow of King's College. 

 AVith Plates I. and II. 



The opportunity of investigating the development of Alcyoni- 

 dium was due to the kindness of Prof. H. de Lacaze-Duthiers, who 

 permitted me to make use of the Zoological Laboratory at Roscoff 

 during the summer of 1883. I desire to express my best thanks 

 for the hospitality so courteously extended to me on that occasion, 

 and to mention my agreeable recollections of the uniform kind- 

 ness with which I was treated, during my stay at Roscoff, by 

 Prof, de Lacaze-Duthiers himself and by all the members of his 

 staff. 



Alcyonidium polyoum is extremely abundant on the Fucus 

 serratus which grows on the rocks exposed at low water in the 

 Riviere de Penze', near Roscoff; its embryos were obtained in 

 abundance during the months of July and August. 



The species was first described by Hassall (7), under the name 

 of Sarcochitum polyoum, but is included by Hincks (8) in the 

 genus Alcyonidium. The form which occurs in the Rivifere de 

 Penze has been identified by Joliet (9) as >S. jwlyoum, and I 

 can depend on the accuracy of the statement made to me by 

 M. Charles Marty, of the Zoological Laboratory at Roscoff, that 

 my own specimens belong to the species described by Joliet from 

 the same locality. I mention this fact, since the description given 

 by Hassall and Hincks is in need of a few corrections, if their 



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