sponges from South Australia. 121 



24. Polymastia massab's. 



Massive, irregularly hemispherical, truncated (? cut off by 

 the dredge) at the base ; scattered over with small wart-like 

 conical processes, like mamillte in miniature, not being more 

 than -^ in. long. Consistence compact, firm. Colour when 

 fresh " purplish brown," now light yellow-grey throughout. 

 Surface smooth. Vents in plurality, partly at the ends of the 

 warty processes and partly on a level with the surface. Spi- 

 cules of two forms, viz. : — 1, skeletal, acuate, very long, 130 

 by |-6000th in. ; 2, subpin-like, 30 by i-6000th and under ; 

 the former in bundles radiating from the body, and the latter 

 confined to the surface, wliere they form a layer intermingled 

 with the points of the skeletal bundles. Structure compact, 

 traversed by the canals of the excretory systems, whicli open 

 at the vents mentioned. Size of specimen 1^ in. high by 

 3x3 horizontally. 

 Depth 19 fath. 



Obs. The raamilliform processes in this species differ in 

 structure from those of the foregoing species and its varie- 

 ties, inasmuch as " the vents " are distinctly in some of 

 the mamilliform processes, which then seem to be entirely 

 devoted to them, while in others the same kind of structure 

 prevails as in PolymaMia hicolor &6. 



Group 14. Track YIN A (new group). 



25. Trachya glohosa. 



Globular, stipitate ; stem thick, cylindrical. Consistence 

 firm, unyielding. Colour when fresh " bright ochre-yellow," 

 now whitish grey. Surface smooth, but uneven, from the 

 dermal layer overlying slight elevations of the subjacent 

 structure. Vents scattered round the summit coronally. Spi- 

 cules of two forms, viz. : — 1, skeletal, acerate, exceedingly 

 long, fusiform, gradually diminishing on each side to a very 

 fine point, 1000 by 9-6000ths in., or about ~ in. long ; 2, flesh- 

 sj)icule, bihamate (fibula), C- and S-shaped, very minute, viz. 

 about 2-6000ths in. long ; the former arranged in bundles 

 radiating from a condensed centre to the circumference, the 

 latter confined to the sarcode. Structure from without 

 inwards consisting of a thick dermis, followed by a radiating 

 arrangement of the skeletal spicules in bundles from the con- 

 densed centre to the circumference, imbedded in sarcode, 

 which is abundantly traversed by excretory canals, especially 

 towards the border. Size of head about 2,\ in. in diameter; 

 stem, which is truncated (? cut off by the dredge), ^ in. in 

 diameter. 



Depth 19 fath. 

 Ann. & Mag. N. Hist. Ser. 5. Vol. xvii. 9 



