REPORT ON THE MONAXONIDA. 179 



but rather woolly. Surface even and fairly smooth where intact. Dermal membrane 

 thin and transparent, mostly abraded. Oscula minute, arranged along the branches 

 in small groups, which often have radiating cracks proceeding from them, and thus 

 acquire a stellate appearance. Pores scattered. 



Skeleton. — Fibre not very distinct ; several main fibres run up the centre of each 

 branch, not very distinct from one another, forming a kind of ill-defined central axis 

 from which primary fibres radiate at more or less acute angles towards the surface, where 

 they terminate in dense brushes of stylote spicules. The fibre itself, though not very 

 weU defined, is clearly arranged on the Axinellid plan, i.e., it consists of stylote spicules 

 whose bases lie together in the centre of the fibre while their apices project outwards 

 and upwards at acute angles. The primary fibres are everywhere linked together by 

 individual spicules, which commonly lie at right angles to them in the horizontal plane. 

 In the centre of the branch there seems to be a fair development of horny cementing 

 substance. 



Spicules. — Megasclera; these are, almost exclusively, short, stout, slightly curved, 

 rather abruptly pointed styli, very constant in size, measuring about 0"28 by 0'024 mm. 

 Occasionally also one meets with a strongylote spicule of about the same size, l^ut these 

 are of rare occurrence and should probably be regarded merely as abnormal forms 

 of the styli. 



This is a fine, showy species, with a very characteristic external form. 



The spiculation is characterised by its simplicity, and by the unusual constancy in size 

 of the styli ; the arrangement of the skeleton, however, in columns radiating from a 

 loose central axis, seems to mark the true position of the species as a member of the 

 genus Axinella. 



Locality. — Port Jackson ; depth, 30 to 35 fathoms. One specimen. 



Axinella balfourensis, Ridley and Dendy (PI. XXXIII. fig. 1). 



1886. AxineUa balfourensis, Ridley and Dendy, Ann. and Mag. Nat. Hist., ser. 5, vol. xviii. 



p. 480. 



Sponge (PI. XXXIII. fig. 1) erect, stipitate, consisting of a spreading, much branched 

 root surmounted by a long, cylincbical stem, which at a height of 112 mm. above the 

 root divides into two branches, each branch again dichotomising ; altogether giving rise to 

 a large head of long, thick, dichotomously branching, finger-like processes, the different 

 In-anches often anastomosing with one another, and terminating in tapering points. 

 Total height of specimen (including root) 350 mm.; diameter of stem a little over 6 mm. 

 Diameter of finger-like processes in head 8 mm. or a little more. Colour in spii-it 

 yellowish-grey. Texture of stem firm and compact ; of finger-like processes in head ex- 

 ceedingly soft and spongy, fragile. Surface very slightly hispid, fairly smooth. Dermal 



