EEPOET ON THE MONAXONTDA. 41 



Gellius glacialis, Eidley and Dendy (PI. VIII. fig. 7 ; PI. XIII. figs. 1, 15, 19). 



1886. GcUius glacial is, Eidley and Dendy, Ann. and jMag. Nat. Hist., sur. 5, vol. xviii. p. 333. 



Sponge (PI. VIII. fig. 7) massive, sessile; shape very various, globular, lobate, or 

 cylindrical. Size, ranging up to 81 mm. long by about 31 mm. broad (a roughly 

 cylindrical specimen). Colour in spirit very pale greyish-yellow. Texture firm, but 

 very brittle. (The sj^onge has very much the appearance of a mass of half-melted snow, 

 whence the specific name.) Surface even, but rather rough ; dermal layer distinct, 

 readily flaking ofi"; composed of the dermal membrane supported by a reticulation of 

 spicules. The dermal membrane itself is extremely delicate and has almost everywhere 

 been removed, probably washed ofi' in coming up in the dredge. It is further 

 supported by abundant, large sigmata. Pores ; as far as can be made out these are 

 rather large and not abundant. Oscula large, irregularly scattered, having their 

 margins flush with the surface of the sponge. 



Skeleton. — {a) Dermal (PL XIII. fig. 19); consisting of a very beautiful, almost 

 unispicular reticulation of large, stout, oxeote spicules, {h) Main ; consisting of a very 

 loose and irregular reticulation of spicules like those forming the dermal layer, and of 

 about the same size (PI. XIII. fig. 1). Sometimes a few spicules lie more or less 

 parallel and close to one another, so as to form a rudimentary spiculo-fibre. The 

 whole reticulation is very delicate and fragile, and a very small amount of cementing 

 substance (spongin) is present at the points where the spicules touch one another, at 

 or near their apices. 



Spicules. — («) Megasclera ; large oxea (PL XIII. fig. 1), slightly curved, and tapering 

 rather abruptly to a sharp point at each end ; size, 0*65 by 0'036 mm. (h) Microsclera ; 

 numerous, large sigmata (PL XIII. fig. 15) of the usual shape, occurring very abundantly 

 in the dermal membrane ; size up to 0"07 by 0'0063 mm. Smaller ones, probably 

 young forms, also occur. 



This species may be most easily recognised by its external appearance. It is 

 probably nearly related to Gelliiis carduus, nobis, but has not the sharp and projecting 

 edges to the oscula which characterise that species. It is exceedingly delicate. In the 

 specimens before us the soft parts have been almost entirely washed away, leaving a 

 very fragile skeleton. Owing to the absence of soft parts and of any coarse fibre the 

 specimens have a pecuhar translucent look. 



Locality.— ^i&tion 142, December 18, 1873; lat. 35° 4' S., long. 18° 37' E.; 

 AgulhasBank; dejjth, 150 fathoms; bottom, green sand; bottom temperature, 47°'0. 

 About twenty-five specimens. 



(ZOOL. CHALL. EXP. — PAET LIX. — 1887.) Nun 6 



