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



Ciocalypta hyaloderma, Ridley and Deudy (PL XXXIII. figs. 2, 2a). 



1886. Ciocalypta hyaloderma, Ridley and Dendy, Ann. and Mag. Nat. Hist., ser. 5, vol. xviii. 



p. 479. 



Sponge (PI. XXXIII. fig. 2) cylindrical, or subcylindiical ; ramose. The largest piece 

 in the collection consists of a very short, stout, basal portion (evidently broken off Ijelow), 

 from which two short branches diverge at a very wide angle ; distance from apex of one 

 branch to that of the other 40 mm. ; diameter of branches from about 8 to 13 mm. A 

 second fragment is cylindrical, measuring 44 mm. in length by 10 mm. in diameter ; 

 it gives off a single branch near the middle, of which the stump only remains. Colour 

 in spirit dirty brown. Texture very delicate and fragile. Surface fairly even. 

 Dermal membrane (PL XXXIII. fig. 2a) very delicate, absolutely transparent ; supported 

 at some distance from the underlying tissues (which can be distinctly seen through it) on 

 slender pillars ; marked -ndth numerous little white stars, caused by the spicules which 

 compose the supporting pillars radiating as they abut against it and forming the principal 

 nodes in a well-developed dermal reticulation of spiculo-fibre. Oscula (PL XXXIII. 

 fig. 2a) scattered over the branches, of fair size, each surrounded by a prominent mem- 

 branous collar; a1)out 2 mm. in diameter. Pores, round openings in the dermal 

 membrane, about 0'05 mm. in diameter ; rather difficult to make out on account of 

 the extreme transparency of the dermal membrane even when examined in spirit. 



Skeleton. — Consisting, in the solid central portion, of a loose reticulation of bands of 

 spiculo-fibre and detached spicules, with a very marked preponderance of longitudinal 

 fibres. Short pillars of spiculo-fibre, as already stated, connect the central portion of the 

 sponge with the dermal membrane ; the spicules at the distal ends of these pillars 

 expand into divergent Inrushes which form each a " node " in the dermal reticulation. 

 The dermal reticulation is very well developed and very wide meshed, consisting of 

 usually stout bands of spiculo-fibre, radiating, roughly speaking, from the distal ends of 

 the supporting pillars, and branching and anastomosing with one another. 



Spicules. — Megasclera; of one form only ; viz., smooth, usually slightly curved, fairl}' 

 gradually but not very sharply pointed styli, commonly narrowing slightly towards the 

 base; these are variable in size, in the dermal reticulation they commonly measure about 

 0"53 by 0'014 mm., while in the central portion of the sponge they measure about TO by 

 0-037 mm. 



This species certainly comes very near to the original type of the genus, viz., 

 Ciocalypta penicillus, Bowerbank ; but is distinguished by its different growth and much 

 more delicate structure throughout ; the central axis is not so dense as in that species, and 

 the dermal reticulation is not so confused and has much wider meshes.^ The spicules 

 also attain a considerably larger size than in Ciocalypta ijenicillus. 



' In this respect Bowerbank's Ciocalypta led, which is no douht a very young specimen of Ciomlyfta pcnicilluti, 

 resembles the present species. 



