SPONGES.-HALLMANN. 



11)7 



either remain attached to it along vertical lines, or become, 

 distally separated from it as growth proceeds. The external 

 appearance of the sponge is accordingly subject to considerable 

 variation, but in no case is there positive evidence of a tend- 

 ency to form linear branches or processes. The degree of 

 variability of the spicules is such that doubt might reasonably 

 be held as to whether all these forms really belong to a single 

 variety ; and consequently, in the absence of sufficient evidence 

 upon which to base a positive conclusion, but being compelled, 

 one might say, to take cognisance of them, I adopt the pre- 



Fig. 40 — A', typiciis var. obesus. a Basal ends of auxiliary spicules 

 of a typical specimen, a' Acanthostyles of ditto. b Acanthostyles 

 from a co-t}'pical specimen, c Basal ends of accessory spicules of a 

 non-typical specimen, c' Acanthostyles of ditto, d, e Acanthostyles 

 from two other non-typical specimens. f Larger chela from a typical 

 specimen. 



caution of specifying which of them are to be regarded as 

 typical, viz., those which Whitelegge evidently had under 

 consideration when he wrote, ^ "This species has a superficial 

 resemblance to Clathria aiistralis, Lendenfeld. " One of the 

 characteristics of the sponge to which Whitelegge ihus refers 

 and which is described in the present paper (p. i6o) as Crella 

 incrustans var. arenacea, is the presence on the surface of 



1 Whitelegge— Rec. Austr. Mus.. iv.. 2, 1901, p. 80. 



