ALCYONIDIUM TOLYOUM. 501 



the mass ; figure 10 is taken from two zooecia which had 

 fallen from a specimen preserved in fluid. In the inner 

 and older parts of the crust they lie more closely together, 

 but are still very distinct and retain much the same 

 form. The lower part of the cell is ovate and recumbent ; 

 the anterior extremity is bent upwards and suberect, and 

 forms the neck of the flask-shaped figiire. As Alder has 

 remarked, this species in certain states " looks somewhat 

 like a cluster of separate animals/^ 



Alcyonidium polyoum, Hassall. 



Plate LXIX. fig. 9. 



Sarcochitum polyoum, Hassall, Ann. N. H. vii. 484 : JoJinst. B. Z. ed. 2, 

 365, pi. Ixxi. 



Zoarium forming a thin fleshy crust, covered with nume- 

 rous large papillae of irregular form and unequal size, 

 from which the polypides issue. Ova scattered singly 

 through the zoarium. 



Polypide with 20 tentacles. 



Habitat. On Fucus serratus &c., and on shells and 

 stones. 



Localities. Dublin Bay (Hassall) : Northumberland, 

 on the underside of stones, tide-pools (Alder) *. 



Geographical Distribution. Roscoff, especially on 

 Rhodhymenia palrnata and Fucus serratus, very fine ( Joliet) . 



A. polyoum is chiefly distinguished from A. my till by 



* Mr. Alder was ratbef doubtful as to his identification of the Northum- 

 berland form with the present species. A. polyoum is included in my 

 Devon Catalogue ; but I am now inclined to think tJiat the specimens which 

 I referred to it really belonged to A. mytili. 



