?36 



ENDEAVOUR" SCIENTIFIC EESULTS. 



spicules occur in the dermal layer as "radiating tufts" 

 is misleading, since it would imply some degree of regu- 

 larity in their arrangement and might suggest that the 

 "tufts" are disposed vertically. As a matter of fact these 

 spicules lie more or less horizontally, and although penicillate 

 groups and parallel bundles occur, they are, on the whole, 

 scattered without order. Chehe and toxa are plentifully dis- 

 tributed throughout the sponge ; but in the dermal layer, in 

 which the chela? are particularly abundant, toxa are rare or 

 absent. An interesting point in connection with the megas- 

 cleres is the extreme \ariability of size, not only of the 

 principal, but also of the auxiliary, spicules ; although the 

 former may attain to a length of over 600 ^/, indi^■iduals ex- 

 ceeding 400 )i are comparatively rare. 



."^ 



Fig. A9a—Clathria atriiop/iora. a Toxa. b Chela, 

 c Acantho.styles. d Basal ends of auxiliary tylo- 

 stvles. 



This species is distinguished from all the preceding species 

 herein described on account of the very conspicuous part which 

 the megascleres play, in comparison with the spongin, in the 

 composition of the skeleton. 



Z.0C5. -Coa.st of New South Wales; Shoalhaven Bight, 

 15-45 fms. ("Endeavour"); off Barranjoey, -'5-28 fms. 

 ("Thetis"). 



