180 THE VOYAGE OF H.M.S. CHALLENGER. 



membrane thin and very delicate. Oscrda rather small, scattered up and down the soft, 

 finger-like processes. Pores (? thickly scattered over the finger-like processes). 



Skeleton. — Loose separate bands of spiculo-fibre run up the centre of each branch and 

 form an ill-defined axis, from which radiate other loose, thin fibres towards the surface, 

 crossed irregularly and sparingly by separate spicules. At the surface are numerous 

 loose, radiating brushes of stylote spicules, whose points project slightly lieyond the 

 dermal membrane. The same arrangement holds good, with very slight modification, in 

 the stem. 



Spicules. — Mcgasclera ; very slender, smooth, straight or very slightly curved styli, 

 .sharply and gradually pointed at the apex ; size about 0'42 by 0"0075 mm.; of the same 

 shape both in the dermal tufts and in the main skeleton, but in the former of only about 

 half the size. The entire skeleton seems singularly insufficient for the requirements of 

 so large a sponge, and, as a consequence, the sponge is very flexible, soft and fragile. 



This seems to be a very aberrant species of the genus, as indicated both by its external 

 form and by the extreme sparseness of the skeleton. 



Locality. — Balfour Bay, Kerguelen ; depth, 20 to 60 fathoms. One specimen. 



Axinella mariana, Eidley and Dendy (PL XXXIV. fig. 1 ; PL XL. fig. 2). 



1886. Axinella mariana, Ridley and Deudy, Ann. and Mag. Nat. Hist., ser. 5, vol. xviii. p. 480. 



Sponge (PL XXXIV. fig. 1) of delicate growth, erect, proliferously branched; stem 

 short, rather slender ; branches rather slender, somewhat flattened. Total height 52 

 mm., breadth about the same. Length of stem 13 mm., diameter 3 mm. Colour iu 

 spirit greyish-yeUow. Texture very soft and friable externally, internally pretty tough. 

 Surface of branches echinated by abundant, very long, projecting spicules. 



Skeleton. — In the centre of each branch there is a fairly dense core of irregularly 

 arranged, short, bent, stylote spicules. In this confused mass are imbedded the bases of 

 very large, stout styli, whose apices project far beyond the surface of the sponge. 



Spicxdes. — Megasclera; of tw^o kinds — (l) short, smooth (rarely slightly spincd) styli 

 or subtylostyli, each with a single sharp bend near the base (PL XL. fig. 2, &), finely and 

 gradually pointed at the apex ; size about 0"3 by 0"013 mm. (Imt variable). (2) Very 

 long, smooth styli or tylostyli (PI. XL. fig. 2, a), usually with a slight bend towards the 

 base, very gradually and finely pointed at the apex; size about 2*2 by 0"03 mm.; echinat- 

 ing the surface of the sponge and with their own bases echinated by the smaller styli. 



This is a pretty little species, distinguished by its external form and by the peculinr 

 shape of the smaller stylote spicule, which seems to be homologous with the " vermi- 

 cular " spicule of Axinella erecta, &c. 



Locality. — Off Marion Island ; depth, 50 to 75 fathoms. One specimen. 



