14 THOMSON, The Pennatulaceae of 'the Cape of 'Good Hope. 



2. With autozooid calyces. 

 Fam. 2. Echinoptilidae. 



(a) Autozooids completely radially arranged. Actinop- 



tilum. 



(b) Autozooids radially arranged, but commencement of 



external bilateral symmetry. Echinoptilum. 



This classification raises the doubt whether different 

 authorities on this group are agreed in their conceptions of 

 a calyx. Kukenthal's definition of a calyx is as follows : 

 " Unter einem Polypkelche verstehen wir das verdickte 

 untere Mauerblatt des Polypen, welches mehr oder minder 

 scharf von dem oberen abgesetzt ist, und in welchen sich 

 der obere weichhautigere Polypteil zuruckziehen lassen." 

 He regards the presence or absence of a calyx so under- 

 stood as a character of families or genera. It may be 

 stated in passing that if my specimen, Actinoptilum molte, 

 Pieter Faure, No. 13,103, is adequately preserved, then 

 according to the latter part of this definition the distinc- 

 tion between the Fam. Veretillidae and Echinoptilidae 

 breaks down. 



Kukenthal also holds that the form and arrangement 

 of the spicules is characteristic of each species, and that 

 the presence or absence of spicules in the tentacles is 

 important in this connection. In my opinion, other 

 points being similar, the presence or absence of spicules 

 in the tentacles would only constitute a variety, especially 

 if these spicules were of the minute corpuscular type. In 

 the genera Actinoptilum and Echinoptilum an important 

 point is not so much the presence or absence of a ventral 

 groove on the rachis, but the radial or non-radial sym- 

 metry of the autozooids. I hold that while the genus 

 Actinoptilum shows affinities with the genus Echinoptilum, 

 it also exhibits as close affinities with Cavemularia, more 



