562 



DR J. STUART THOMSON ON 



(1) The stalk part is not very distinct, as the polyps sometimes originate far down 

 on the colony ; (2) there are spicules in the axes of the tentacles ; and (3) numerous 

 pinnules occur on the inner surface of the latter, a feature which also appears in the 

 p-enus Sinularia. 



Metalcyonium patagonicum, May. 

 ? Alcyonium antarcticum, Hickson. 



Plate I. fig. 8 ; PI. II. fig. 12 ; PL III. figs. 22, 26-29 ; PL IV. figs. 30-32. 



This description is based on a number of specimens from different localities. It 

 must be regarded as a species which is fairly common in South African seas. The 

 specimens show a very obvious external resemblance in form and even in colouring to 

 young mushrooms, especially to the so-called Fly-mushroom, Amanita muscaria, and 

 to the bulbous mushroom, Amanita bulbosa. 



The colony shows three main parts : — Firstly, a globular head (pileus) bearing 

 numerous polyps ; secondly, a barren stalk or trunk which may be termed the " stipe"; 

 and thirdly, at the base of the latter, a horizontally expanded part, which encrusts 

 various objects, organic and inorganic. In several of my specimens, this last part is not 

 present, having been torn away in dredging. 



The dimensions of three of the larger specimens were as follows : — ■ 





Specimen A 



Specimen B 



Specimen C 





(with yellow 



(with red ten- 



(with red ten- 





tentacles). 



tacles). 



tacles). 



Length of colony, ...... 



25*6 mm. 



29-8 mm. 



37-0 mm. 



Length of globular head (pileus), .... 



13-6 „ 



12-0 „ 



13-0 „ 



Diameter of globular head (pileus), 



16-0 „ 



18-0 „ 



17-0 „ 



Length of trunk (stipe), ..... 



12-0 „ 



17-8 „ 



24-0 „ 



Diameter of trunk (stipe), ..... 



11-0 „ 



10-5 „ 



13-0 „ 



Diameter of fairly expanded polyp taken at calyx, . 



3-0 „ 



20 „ 



2-0 „ 



Diameter of contracted polyp taken at calyx, 



i-o „ 



1-0 „ 



1-0 „ 



The colours of specimens vary considerably, and are in all cases produced by the 

 spicules ; the following four variations of colour may be noted : — 





Specimen A. 



Specimen B. 



Specimen C. 



Specimen D. 



Ground colour of head (pileus), . 



Yellow. 



Red. 



Yellow or 

 white. 



Yellow or 

 white. 



Tentacles, 



j> 



Red and 

 orange. 



Red. 



Yellow. 



Calyx, 



>) 



Orange. 



j) 



Red. 



Internal wall of stomodaeum, 



White or 

 yellow. 



Red. 



)> 



i> 



Internal ccenenehyma of head (pileus), 



Red or 

 white. 



Mostly red. 







Kxternal trunk (upper part of), . 



White. 



Red. 



Brownish. 



Brownish. 



External trunk (lower part of), . 



Red. 



>) 



Red. 



Red. 



Internal trunk, ..... 



Red and 

 white. 



Mostly red. 







