398 Mr. W. J. Sollas on the 



irregular bifurcated rays, shaft 0"13 inch long, rays 0*034 inch 

 long (PI. XVII. fig. 9). 



Slender long-shafted Spicules. — (i) a simple sharp-pointed 

 acerate, 0*0004 inch thick ; (ii) a trifid spicule with rays 

 recurved anchor-like, 0*0008 inch thick (PI. XVII. fig. 6) ; 

 (iii) a trifid spicule with rays directed forwards, 0*0008 inch 

 thick (PI. XVII. fig. 8). 



Stellates. — (i) a spheero-stellate with a large body and nu- 

 merous short conical rays, 0*0005 inch in diameter (PI. XVII. 

 fig. 12) ; (ii) a stellate with small body and a few long rays, 

 usually about 0-0008 inch in diameter (PI. XVII. fig. 13), 

 but often becoming exceptionally large, as much as 0*0015 

 (PL XVII. fig. 10), or rarely even 0*0027 inch in diameter. 



Globates. — Oblate and prolate ellipsoids, the latter with one 

 minor axis shorter than the other; covered superficially by erect 

 tubercles, having a more or less flattened polygonal summit, 

 from the corners of which minute short slightly recurved spines 

 are produced. Diameter 0*0036 inch (PI. XVII. fig. 14). 



Locality. Kors Fiord, Station No. 23 : 180 fathoms. 



Observations. — A section across the sponge shows a thin 

 rind (0*025 inch thick) enclosing a greyish-yellow mark, 

 which is traversed by numerous canals of various sizes. Those 

 large enough to be plainly visible to the naked eye have 

 smooth glistening walls, concentrically striated by fine ruga? : 

 some take a concentric, others a radiate course, the same canal 

 being concentric in one part of its course and radiate at 

 another. The crypts are very irregular in size, some being 

 markedly larger than others ; they have lost the characters 

 which distinguish them in Stelletta Normani, and appear to 

 be the cut ends of concentric canals, precisely similar to those 

 occurring in the mark, and only differing in being situated 

 immediately beneath the rind; indeed it occurs to one to 

 suggest that both in this instance and in Geodia Barretti the 

 concentric canals are merely the cryptal canals left behind in 

 the progressive increase of the sponge. 



Histology. 



1. The Cortex. — The epidermis consists of a very distinct 

 transparent, colourless, and apparently structureless cuticle, 

 lying quite separate from the succeeding dermal layer; no 

 nuclei nor cell-borders are observable in it (PI. XVII. fig. 11, c). 

 The dermal layer consists of very definite colourless, granular, 

 oval cells, lying quite separate from one another, and forming 

 a layer of variable thickness ; sometimes it thins out altogether 

 and lets down the epidermis into immediate contact with the 

 globate layer ; sometimes, on the other hand, it thickens out 



