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



ending in a third, small, globular head. Total height of specimen 56 mm.; diameter 

 of largest head 15 mm.; diameter of largest peduncle 6 mm. Colour in spirit light, 

 greyish-yellow. Texture solid throughout, hard, incompressible and woody. Surface 

 even, but covered with a velvet-like pile. 



Skeleton. — Radiately arranged, very dense, consisting of closely packed fascicles of 

 spicules radiating towards the surface. There is a dermal crust of thickly packed, pro- 

 jecting, tylostylote spicules, and below this come the main skeleton fascicles, composed 

 mainly of stylote spicules ; (we have been unable to determine with certainty whether any 

 of these large styli project beyond the surface of the sponge and take part in the 

 formation of the velvet-like pile, or whether the latter is formed entirely of tylostylote 

 spicules). The dermal crust of spicules is continuous all over the surface, but every 

 alternate fascicle of the main skeleton stops short a little way below the surface and 

 before it reaches the bottom of the dermal crust, and thus arise a number of fairly 

 definite spaces, devoid of spicules, which seem to be comparable to the subdermal cavities 

 of other Monaxonida. 



Spicules. — Megasclera; (1) tylostyli (PI. XLV. figs. 2a, 26, 2c), straight or nearly 

 so, with well-developed, almost globular heads, fusiform shafts, and sharply and gradually 

 pointed at the apices. These occur mainly in the dermal crust, with their points directed 

 outwards ; a common size for them is about 0*24 by 0"0063 mm., but in this respect they 

 vary extremely, and they pass by a series of transitional stages (both as regards form, 

 size, and position) into (2) the deeper spicules found in the main skeleton fascicles. These 

 spicules are very long, straight, slender, smooth, fusiform styli and subtylostyli (PI. 

 XLV. figs. 2, 2d, 2e), very gradually and sharply pointed at the apices ; size about 1'5 by 

 0"0157 mm.; having their apices generally (? always) directed outwards. 



This is one of those species which appear to mark a transition in external form from 

 Suherites to Stylocordyla. 



Locality. — Ofl:' the south-east coast of Australia. One specimen. 



Suherites mollis, Ridley and Dendy (PI. XLI. fig. 4 ; PI. XLV. figs. 4, 4a, 46, 4c). 



1886. Suherites mollis, Ridley and Dendy, Ann. and Mag. Nat. Hist., ser. 5, vol. xviii. p. 486. 



Sponge (PI. XLL fig. 4) stipitate, with expanded, lobose head. The short stem is 

 attached by a slightly expanded base to a fragment of stone, and is surmounted by the 

 broad, lobose, slightly compressed, suboval head, bifurcating slightly at the top. Total 

 height of sponge 31 mm., length of stem 13 mm.; diameter of same about 2"5 mm.; 

 greatest breath of head about 13 mm. Colour in spirit pale yellow. Texture (of head) 

 very soft and spongy ; of stem, firm, but brittle, scarcely fibrous. Surface even, but 

 minutely hispid. Dermal merahrane distinct. Pores apparently scattered. Oscula (?). 



Skeleton. — (a) The skeleton of the stem ; this consists of a dense, well-defined, central 



