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



rather soft. Surface even but minutely hispid ; with a porous appearance due to the 

 close reticulation of the dermal skeleton. Dermal membrane (1) (nearly all rubbed off). 

 Pores {Tj. Oscula; one specimen shows two small, conical, tubular projections, each with 

 an osculum at the summit (PL XVI. fig. 5, o). 



Skeleton. — (a) Dermal ; a very close and compact reticulation of dense spiculo-fibre, 

 the meshes of the network being about 0"3 mm. and the fibres themselves about 

 0"08 mm. in diameter. Numerous spicules project more or less vertically from the 

 fibres, thus causing the hispid appearance of the surface, (b) Mam; a loose reticulation 

 of dense, stout spiculo-fibre, which branches and anastomoses. As they approach the 

 surface the fibres expand into brushes of spicules upon which the dermal layer rests. 

 The spicules composing the fibres are united together by a fair proportion of spongin. 



Spicules. — (a) Megasclera ; of one kind only, viz., tylostyli (PI. XV. fig. 6), stoutest 

 in the middle, with a small head at one end, separated by a slight constriction from the 

 shaft; tapering rather suddenly to a sharp point at the apex. Size about 0'38 by 

 0"016 mm. (6) Microsclera ; of two kinds; (1) palmate anisochelse (PL XV. fig. 17), 

 rather small for an Esperella, about 0"05 mm. long; with a long, narrow palm at the 

 large end ; (2) large, smooth, simple and contort sigmata (PL XV. fig. 9), measuring 

 about 0-16 by 0-0085 mm. 



This species may he most readUy recognised by the character of the dermal skeleton 

 reticulation. It is represented in the collection by only two fragments, one of which 

 has an interesting and peculiar habit. It has grown around the stem of an Alcyonarian, 

 which it has covered with a very thin horny layer containing the proper spicules of the 

 sponge, the tylostyli being mostly placed longitudinally. This horny coating is easily 

 separable from the Alcyonarian stem, and forms by itself a hollow cylinder from which 

 the skeleton fibres arise. 



This species appears to resemble Esperella velutata, Lbkn. sp., as far as spiculation 

 is concerned, but the descriptions given of the latter are too imperfect for identification 

 and the great difference in locality, the one being found at Port Jackson and the other 

 at Venice, renders it improbable that they are the same species.^ 



Locality. — Off Port Jackson, 30 to 35 fathoms. Two small specimens. 



Esperella nuda, Ridley and Dendy (PL XV. figs. 5, 11, 14 ; PL XVI. fig. 1). 



1886. Esperella nuda, Eidley and Dendy, Ann. and Mag. Nat. Hist., ser. 5, vol. xviii. p. 339. 



Sponge (PL XVI. fig. l) encrusting an irregular mass of dead spiculo-horuy fibre 

 belonging to an Esperella, probably of the same species. Sometimes the naked amber- 

 coloured fibre projects far beyond the surface of the sponge. Colour in spirit pale yeUow. 



1 For Esperella velutata, vide O. Schmidt, Spongien des Adriatischen Meeres, p. 57; also Vosmaer, Notes from 

 the Leyden Museum, vol. ii. p. 141. 



