46 [. [JIM A. 



of diactins which are grouped in thin anastomosing strands. In the 

 rest of octasterophorous species, they consist of moderately large oxy- 

 pentactins, either solely or in union with subtangentially disposed 

 diactins. The proximally directed shafts of these hypodermal pentactins 

 are always smooth ; the four paratangential rays are also smooth or 

 minutely rough (Staurocalyptus), or else armed with biserially arranged, 

 strong, hook-like prongs (Rhabdocah/ptus). The paratangentials are 

 often, though not always, paratropal, i.e. the four rays are, as it were, 

 pushed aside so that they form with one another three more or less acute 

 angles and one wide angle greater than 90° or even 180 c . Similar hypo- 

 dermal pentactins have long been known in Rossella antarctica. As in 

 this species they are generally found in groups of several together. In 

 every such group, proximally directed shafts, accompanied with slender 

 comital diactins, form a more or less compact column or tuft that dips 

 deeply into the parenchymal mass, while the heads composed of paratan- 

 gential rays bring about a star-like figure, in which a number of streaks 

 radiate in all directions from what I will call, for the sake of convenience, 

 the hypodermal centre. It is easy to discover that the pentactin-heads 

 in a hypodermal group lie one above the other and that the one in an 

 upper situation is older and more fully developed than that following 

 next below. The lowest is therefore the youngest, which developes it- 

 self clasping with one of its angles the column of shafts belonging to 

 older pentactins. It is this preexisting shaft-column that disturbs the 

 regularly cruciate development of the head of young pentactins ; hence 

 the paratropal arrangement of paratangential rays. 



The hypodermal pentactins remain in their locus nascendi only in 

 certain species. More usually they are destined to be protruded out- 

 wards through the autodermal layer as prostalia pleuralia. These stand 

 out isolated or in tufts from hypodermal centres ; and, in case they are 

 not shed off, their paratangential rays form a gossamer-like veil at a 

 certain distance from the dermal surface, exactly as is known in the 

 genus Rossella. 



Diactin prostalia are also of common occurrence. These are to be 



