SPONGES PROM COASTAL BEACHES OF N. S. "WALES — "WHITELEQGE. 91 



The main fibres measure from 0*15 to 0-2 mm. in diameter, the 

 smaller branchlets from 0-05 to 001 mm. The axial core of oxeote 

 spicules is very dense and imbedded in much spongin ; the latter 

 is abundantly charged with very spiny styli, many of which are 

 arranged parallel with the axis, but the majority are echinating ; 

 they are exceedingly numerous, so that under a low magnifying 

 power the fibres have a villous appearance. The dermal skeleton 

 consists of a thin layer of smooth oxea, and a thickish external 

 crust of slender, curved, spined styli. 



Megascleres — (a) Smooth straight oxea. Size — 0"18 to 0"2 by 

 0*006 to 0065 mm. (b) Spined echinating styli ; base and lower 

 two-thirds of shaft with numerous often recurved spines ; apex 

 very acute and smooth. Size — 0*1 to 0-14 mm. by 0'0065 to 001 

 mm. (c) Slightly curved spined styli of the dermis and of the 

 ground substance. Size— 0-08 to 0-1 by 0-0055 to 0006 mm. 



Microscleres — Small tridentate isochela^. Size — 0012 to 0015 

 mm. 



Clathria tnacropora, Lendenfeld (Nos. 267 and 290). 

 (Plate xi., fig. 14). 



The types differ from C. australis in their branched or lobate habit. 

 The description accurately describes the dry example. It will be 

 noted that the surface is " undulating and grooved," and that the 

 "skeleton consists of a network of mostly longitudinally disposed 

 fibres, which contain an axial bundle of slender oxea and styli, the 

 former being the most abundant." It is not stated whether the styli 

 are spined or smooth. I failed to find any of the latter either in situ 

 or in spicules obtained by boiling. With regard to the oscula "5 

 mm. wide," I am in doubt as to their real nature, as most of them 

 are inhabited by a small Isopod — a species of Oymodoce — -which is 

 found infesting many sponges on the coast. This is particularly 

 the case with E. IcBvis, which often appears as if it had been 

 riddled by a shot gun, the holes in the flabellate forms being 

 continued through the frond. The spicules obtained by boiling 

 yield the following measurements : — 



Megascleres — (a) Generally straight smooth oxea. Size — 18 

 to 0-2" by 0-0055 to 0-006 mm. (b) Echinating spined styli 01 to 

 0-12 by 0-008 to 0-01 mm. (c) Curved spined styli 0-08 to 009 

 by 0-006 mm. 



Microscleres — Small, tridentate isochelse 0-012 to 0-016 mm. 



Echinonema Icevis, Lendenfeld (Nos. 213, 278, 443). 

 (Plate xi., fig. 14a). 



The types conform to the description, excepting that the axial 

 spicules of the fibres are oxea, and not styli. Here again we 

 note that the "skeleton consists of irregularly curved, for the most 

 part longitudinally extending fibres." 



Megascleres — (a) Straight smooth oxea. Size — 0-18 up to 02 

 by 0-0055 to 0-006 mm. (b) Spined echinating styli. Size— O'l 



