EHABDOCALYPTUS CAPILLATUS. 285 



usually of two rays, but occasionally of three, belonging to as 

 many ditlerent spicules and running side by side. 

 No special canalaria are found. 



The oxyheT: asters occur in abundance in all parts of the 

 sponge-wall. In a few instances I have seen them even outside 

 of the dermal layer, and frequently they are borne, together with ' 

 some discoctasters, on the free proximal rays of gastralia. They 

 are mostly normally developed, the terminals being in general 

 slender, minutely rough and nearly straight or slightly wavy. 

 Diameter, 106-136«. The oxyhexasters in the periphery of the 

 wall are somewhat differently characterized from those in the 

 deep parts. The former (PL XXIL, figs. 7 and 8; also PL 

 XXIIL, fig. 19) are on the Avhole slightly larger ; their princii)als 

 are of a perceptible length ; and there occur usually 3, sometimes 

 4, terminals to a principal. In the latter (figs. 14 and 15) the 

 principals have almost disappeared ; the terminals are somewhat 

 stronger but less in number, there being generally 2 or rarely 3 

 of them to a principal. Occasionally the deeply situated oxy- 

 hexasters are hemihexactiuose and only rarely hexactinose ; more- 

 over, their terminals may sometimes be provided at base with 

 some distinctly barb-like microtubercles, — all of which seems never 

 to be the case with the peripheral oxyhexasters. In a certain 

 specimen I have found the terminals in some of the subgastral 

 oxyhexasters supplied with basal barbs about as prominently 

 developed as in R. mollis, but in any case this seems to be a 

 character varying much according to individuals as well as within 

 the same individual. 



In the smallest specimen I have had (3 nnn. in size), oxy- 

 hexasters were already numerously present, but all these agreed in 



