SPONGES.-HALLMANN. 



279 



Judging from the rather abundant material at my disposal, 

 it would seem that decrease in the frequency of branching and 

 anastomosis, increase in the length of branches and the as- 

 sumption of a more erect habit, the tendency of branches to 

 become compressed, of cell-apertures to become elongated, 

 and of the external edges of the superficial lamellae to become 

 jagged — are concomitant variations. 



The sponge is of fibrous texture, and, in the dry state, 

 tough and resilient. Some specimens are of an intense purplish 

 colour owing to the presence of a sym- 

 biotic alga ; otherwise the colour of the 

 dry sponge varies between yellowish- 

 grey and pale brown. 



pi 



n 



The skeleton is a compact reticulation 

 of slender horny fibres readily distin- 

 guishable into main and connecting. 

 The main fibres, which run (in approxi- 

 mate parallelism) in the direction of 

 growth of the lamella?, contain a meagre 

 core of (principal) styli ; at the outer 

 or growing edge of any lamella, their 

 terminal spicules form a slightl}' pro- 

 jecting tuft. The connecting fibres to 

 some extent interreticulate irregularly 

 between the main fibres and are usually 

 aspiculous. The echinating styli, 

 which — contrary to the statement of 

 Whitelegge — are in no way different 

 from those within the fibres, appear to 

 be entirely confined to the outer side of 

 the fibres which lie immediately beneath 

 the lateral surfaces of the lamellae. The 

 auxiliary megascleres are strongyla — 

 not subtvlostvli, as previously stated. 



In none of the specimens which I have examined have I been 

 able to detect chelae. Whitelegge, however, has observed "in 

 well-preserved specimens" a few scattered isochela? 10 /i in 

 length. 



A point worthy of special note is the relatively great varia- 

 bility in the maximum size (95 x 5 to 120 x 8 ]i) of the principal 

 megascleres ; and in reference thereto I might mention that, 

 between specimens which showed the opposite extremes in this 

 particular, I have been unable to discern any difference what- 

 ever in external characters 



Hab. — Coast of New South Wales, in shallow water (Austr. 

 Mus. Coll.). 



Fig. 62 — £. ratnosa 

 a Principal styles. b 

 Auxiliary strongyle. 



