124 ZOOLOGICAL COLLECTIONS MADE DURING [Jail. 4, 



Tedania tenuicapitata, sp. II. (Plate XI. fig. 1.) 



Massive, almost white. Surface bearing scattered shallow pits 

 from about -1/ to 1 millim. in diameter. Texture very soft and 

 fragile. Vents small, scattered. Pores scattered. Main skeleton a 

 very loose network of spicules, with triangular to polygonal meshes, 

 extending from base to surface, crossed at nodes by spiculo-fibres lying 

 parallel to surface ; sides of meshes formed by groups of 2 to 5 acuate 

 spicules (sometimes of cylindrical spicules in whole or in part), scarcely 

 touching. Dermal skeleton composed of sheaves of 20 or more cylin- 

 drical spicules, closely aggregated at one end, and radiating outwards 

 with the other over the surface. Parenchyma very pale yellow to 

 colourless, finely granular. Skeleton-spicules of two kinds, viz. : — 

 (i) smooth curved acuate, tapering to a sharp point from a distance 

 of about 6 diameters from the point, size '38 by '01267 millim. ; and 

 (ii) cylindrical, double-headed, smooth, heads about one third as 

 broad again as shaft, and oval, drawn out to a point, occurring in 

 main skeleton, and alone forming dermal skeleton, size '2787 by 

 •006334 milUm. Flesh-spicules acerate, tapering from centre to 

 very fine points, roughened almost imperceptibly on surface, one 

 end slightly the stouter, scattered, size '316 by •0021114 millim. 



Examined. In spirit, and by mounting in balsam. 



External Characters. The single specimen forms a small subpyra- 

 midal mass, whose four uninjured faces form rounded angles of about 

 120° with one another. It appears to have been broken from a 

 mass sessile by a broad triangular base. Among the numerous 

 small pits of the surface, in which many of the pores are collected, 

 and between which the Sponge forms insignificant ridges, are dis- 

 tributed the five vents which are still left. Three of these are close 

 to the apex ; they open on the surface level, and penetrate straight 

 into the Sponge to a depth of 3 to 8 millims., where they suddenly 

 terminate ; they are oval, and 1'5 to 2 millims. in diameter. The 

 pores lie on the ridges and in the small surface-pits. 



The main skeleton is very vague, the spicules of the fibre being 

 hardly in contact ; it consists generally of the stout acuates ; but 

 sometimes groups of 6 to 10 cylindricals take their places, or they 

 are mixed with a few of these ; a horizontal network of stout acuates 

 occurs throughout, but is especially developed just below the dermis. 

 The dermal-skeleton bundles appear to radiate from certain centres 

 with more or less regularity. 



The parenchyma is very transparent, and is sufficiently well pre- 

 served to show, in Canada balsam, numerous round nuclei, of about 

 •0095 millim. diameter, transparent, and uucleolated. 



The cylindrical spicule differs from that of all hitherto recognized 

 species of the genus in being terminally pointed ; the heads are very 

 slightly marked and suboval in outline, and are not microspined 

 as in the Mediterranean and Malacca species already known. The 

 fine acerate has, as in other species, one end stouter than the other, 

 though very slightly so : the roughening of the surface is often im- 

 perceptible ; it takes the form, as far as can be made out, of sub- 

 spiral scratches. 



