8 THOMSON, The Pennatulaceae of the Cape of Good Hope. 



The dimensions of the largest specimens are as 

 follows : — 



Entire length of colony 133 mm., length of rachis 

 105 mm., breadth of rachis 14 mm., length of stalk 

 28 mm., breadth of stalk 10 mm., relative length of stalk 

 and rachis 1:3 or 1:4, length of autozooid calyx 

 1 to 2 mm. 



The spicules from the outer and inner part of the 

 stalk, from the outer and inner part of the rachis and 

 from the calyces are essentially similar to those described 

 and figured by Ktikenthal for Actinoptilum violle. 



There can be little doubt that these are true speci- 

 mens of Actinoptilum violle which possess in the ventral 

 groove of the rachis a feature of peculiar interest. The 

 presence of a groove has not hitherto been observed in 

 any Actinoptilum, and its presence in the genus Echi- 

 noptilum and absence in Actinoptilum has been held to 

 be an important diagnostic character. This groove com- 

 mences at the upper end of the stalk, and extends varying 

 distances in different specimens, namely from 7 to 33 mm. 

 The arrangement and degree of development of the auto- 

 zooids is also slightly modified on each side of the groove. 



The specimens are, however, distinct from Echi- 

 noptilum in the smaller calyx, in the very slight groove 

 and by the autozooids being developed in an almost 

 completely radial manner. In this connection, I have 

 been able to refer to a very distinctive new example of 

 the genus EcJiinoptilum in the Siboga collection which 

 has been named E. roseum by Hickson. 



Specimen A. 



Actinoptilum mollc, Kiikth. var. zonatum. The 

 number indicating the exact locality had unfortunately 

 become obliterated in the formalin. 



