368 Prof. Hichson, On Alcyonaria in the Cambridge Museum 



Pseudocladochonus hicksoni Versluys. 



This very interesting Alcyonarian was first described liy 

 Versluys from the collections of the Siboga Expedition near Ceram 

 and Halmaheira*. It exhibits a curious similarity in its method 

 of gemmation and general form to the fossils belonging to the 

 family Auloporidae and particularly to the genus Cladochonus 

 from the carboniferous strata ; but according to Versluys, who has 

 made an elaborate study of the genus and of the Auloporidae, it 

 affords us an example of convergence rather than one of genetic 

 affinity with the fossil family. 



In a small collection of Alcyonaria from the Uraga Channel 

 near Tokyo, Japan 40-200 fathoms, I found a few small specimens 

 of this species which exhibit all the principal characters described 

 in detail by Versluys. 



The size of the retracted zooids 2 mm. x 1 mm. and the dia- 

 meter of the stems from which they arise 1 mm. are the same as 

 in the type. 



The yellow bands where the stem is shghtly constricted just 

 above the origin of the zooids can be clearly seen in some of the 

 older fragments but are obscure in the younger branches. Sections 

 through the stem show an arrangement of solenia divided by septa 

 similar to that of the type and the precise arrangement also seems 

 to vary in different parts of the stem. In one of my sections there 

 are four septa meeting in a central column, in another eight septa 

 which do not meet in the centre, but show some fusions of their 

 free borders. There can be little doubt that the 4-septate condition 

 of the first-named section has been derived from an 8-septate 

 condition by an increase in the thickness of the septal walls and 

 fusion at the centre. 



The small amount of the material at my disposal has prevented 

 me from making a further investigation of this structure but 

 sufficient has been done to prove that the identification of the 

 genus is correct and that the specimens do not represent an 

 aberrant species of the genus Telesto. 



The only difference that I can observe between the Japanese 

 and the Molluccan specimens is in the character of the spicules. 

 In all the preparations I have made which show clearly isolated 

 spicules or spicules which have not yet become firmly joined with 

 their neighbours to form the soHd wall or septa of the tubes, the 

 spicules of the Japanese specimens possess more numerous and 

 larger spines and tubercles than they do in the type specimens. 

 The length of the larger spicules (c. 0-12 mm.) does not show 

 any material difference but there is such a wide range of variation 

 both in size and shape of the spicules in any one preparation, that 



* Siboga Expedition. Monograph XIII c, 1907. 



