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



ends projecting from the outer surface being usually broken off; piercing the wall per- 

 pendicularly to the longitudinal axis of the Sponge. 



Colour. — Pale-yellowish. 



Habitat. — Station 163a, June 3, 1874 ; off Port Jackson, Australia; depth, 30 to 35 

 fathoms ; rock. 



Amphoriscus elongatus, n. sp. (PL IV. fig. 5 ; PL V. figs, in-ie). 



This species is represented in the Challenger collection by one specimen in the form 

 of an elongated tube, 50 mm. long., 3'5 mm. broad, growing rather narrower towards the 

 lower end ; near its free end the Sponge divides into two tubes, standing close together, 

 and each terminating with a naked osculum. The outer surface is roughened by the 

 cortical spicules, the inner surface is similarly roughened by the apical rays of the gastric 

 cpuadriradiate spicules. The thickness of the walls does not exceed 0"6 mm. By its 

 subdermal quadriradiate spicules the species can be distinguished from Amphoriscus 

 glacialis (Sycaltis glacialis, H.), the corresponding spicules in the form just named being 

 triradiate ; the subgastrie triradiate spicules differentiate this form from Amphoriscus 

 oviparus, urna, chrysalis, &c, the corresponding spicules being represented in these 

 latter species by quadriradiate ones. 



The important anatomical peculiarity of Amphoriscus elongatus, namely, the 

 tendency of the radial tubes to meet in threes, in fours, or in larger numbers around the 

 same shallow invagination of the gastric cavity, is represented on PL IV. fig. 5. 



Skeleton. — The skeleton consists of gastric quadriradiate, of subgastrie triradiate, of 

 subdermal quadriradiate, of dermal triradiate, and of minute dermal acerate spicules, 

 sparsely scattered in the cortex perpendicularly to the outer surface of the Sponge. 



Gastric quadriradiate spicules. — All rays of the same diameter (O016-0 - 02 mm.), either sharply 

 or bluntly pointed ; basal ray straight, reaching 0*45 mm. in length, forming with each 

 lateral ray an angle varying from 115° to 122° ; lateral rays either straight or slightly curved 

 inwards, usual length - 25 mm.; apical ray stout, curved, its length not exceeding 0"18 mm. 



Suogastric triradiate spicules. — Sagittal ; rays of the same dimensions and showing the same 

 variations with regard to their angles as those of the corresponding spicules in Amphor- 

 iscus poculum , the sole distinction concerning the form of the lateral rays, these latter 

 being not angularly curved but undulating. In accordance with the strong development 

 of the subdermal quadriradiate spicules, the subgastrie ones are not numerous, and 

 show a tendency to grow smaller and thinner. 



Subdermal quadriradiate spicules. — Sagittal; all rays sharp-pointed, usually of the same dimen- 

 sions, their average length being 0-6 mm. and diameter 0-07 mm.; basal ray — occasionally 

 rather shorter than lateral rays — straight ; lateral rays slightly curved inwards, each 

 forming with basal ray an angle of about 118° ; apical ray straight, either of the length of 

 facial rays or rather longer. 



