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



apices ; size about 0"31 by 0'0094 mm. (b) Microsclera ; (l) very minute, slender, spined 

 spinilse (PI. XLV. figs. 13a-13(i), with some three or four bends and warty rather than 

 spiny; length about 0"012G mm., diameter about 0*0025 mm. (2) There are also a few 

 much longer and, relatively, much slenderer spined spirulse ; in these it is almost impos- 

 sible to say how many bends there are, they are as a rule simply crooked and rather 

 minutely spined; length about 0*056 mm. These latter are probably merely elongated 

 forms of the smaller kind. The microsclera are, as usual, most abundant in the dermal 

 membrane, where they form a solid crust penetrated by the pores, but they are also fairly 

 plentifully scattered in the deeper tissues of the sponge. 



The tendency to form lobes, shown in some degree by previously described species of 

 the genus, is here carried to an unusual extent. The texture is unusually dense, forming 

 perhaps the most characteristic feature of the species. 



i:oca%.— Station 208, January 17, 1875 ; lat. 11° 37' N., long. 123° 31' E.; 

 Philipj)ine Islands; depth, 18 fathoms; bottom, blue mud. Two fine specimens, and a 

 fragment, containing a very large amount of foreign matter, chiefly shells, which seems 

 to belong to the same species. 



Spirastrella papulosa, Ridley and Dendy (PI. XLI. fig. 5 ; PI. XLV. figs. 11-1 If/). 



1886. Spirastrella papillom, Ridley and Dendy, Ann. and Mag. Nat. Hist., ser. 5, vol. xviii. 



p. 491. 



Sponge (PL XLI. fig. 5) massive, erect, sessile; shape conical, broad at the base and 

 tapering gradually to an obtuse apex, where are situated several large oscula. Near the 

 apex the surface is thrown into deep longitudinal wrinkles. The entire surface, except 

 in the immediate neighbourhood of the oscula, is covered with numerous, closely placed 

 papillae of considerable size ; these show a tendency towards arrangement in longitudinal 

 series ; towards the apex of the sponge they decrease in size. Height of specimen 

 about 150 mm.; breadth at base 100 mm. Colour in spirit grey. Texture fairly firm, 

 but rather spongy and, internally, cavernous. Surface uneven, as described above, with 

 a minutely- reticulate appearance, and harsh to the touch. The reticulate appearance is 

 caused, or at any rate largely helped, by the arrangement of the microsclera, which 

 are thickly scattered through the dermal membrane in such a manner as to leave 

 small rounded patches, the meshes of the reticulation, almost or quite free from their 

 presence. In these areas are situated the pores, and the corresponding arrangement of 

 the underlying subdermal cavities also helps to give the reticulate appearance to the 

 surface. Dermal membrane thin, transparent. Oscula large, six or seven in number, 

 grouped at the summit of the sponge, each about 6 mm. in diameter, sometimes a little 

 more. Pores ; very numerous, rounded openings, thickly placed in the meshes of the 



