290 Mr. R, Kirkpatrick on the MonaxonelUda 



Microscleres: long, smooth rliapliides, separate or in bundles, 

 forming part of the subdermal reticulum, 650 X 2'5/i. 



Short, scattered, spined rhaphides, usually stylote, 162 fju 

 long and about 2'5 /* broad. 



H. V. Wilson describes a species of Oceanap'/a, viz. 

 0. hacillifera, with strongyles, but it has sigmata. 



Oceanopia {Phloeodictyon) singaporensis (Carter) has 

 strongyles in the dermal layer, but oxeas as well as strongyles 

 in the skeleton-tibres, and there are no microscleres. 



The species of the Gelliine genus Rhaphida have oxeas, 

 trichodragmata, and, in one species, toxa ; but there are no 

 fistula?, and there is no subdermal reticulum of spicular fibres. 



LocaUty. Winter Quarters, 130 fath. 



Petrosia fistulata, sp. n. 



Sponge tubular. Surface smooth, showing the roinid 

 0])enings of the inhalant canals about "4 mm. in diameter 

 and close together. 



Inner surface of the tube of the sponge finely or rarely 

 coarsely pilose, and showing the ruund openings of the ex- 

 halant canals about 1 mm. in diameter. Colour in spirit 

 pale yellow. Texture tirm, but slightly compressible. Eury- 

 ])ylous fiagellated chambers spheroidal, 24*5 fju in diameter. 



/Skeleton formed of main fibres proceeding from the inner 

 to the outer surface, joined by secondary fibres one spicule 

 thick, so as to form obscurely quadrangular or hexagonal 

 tubes about '5 mm. in diameter; ends of spicules cemented 

 with spongin. 



Spicuhs. — Oxeas, 492 X 24*4 yu,, bent usually, or curved at 

 centre, subtornote. 



There are four specimens, the two larger being uniformly 

 cylindrical and the smaller ventricose. The largest is 6 cm. 

 long, the diameter being 2°1 cm. and the thickness of the 

 wall 5 mm. 



The dermal membrane roofing over the inhalant orifices is 

 usually supported there by two or three single spicules 

 radiating to the centre. The pores are "95 fx in diameter. 



Small embryos about '76 mm. in diameter occur. The 

 new species comes nearest to the species from Kerguelen, 

 which Carter identified as Thali/si'as sub-tnant/ularisy Duch. 

 & Mich., but which Ixidley and Dendy regarded as synony- 

 mous with Petrosia similis (Ridley & Dendy). 



The spicules of the Antarctic species are very much larger 

 than those of Carter's, and partly in consequence of this the 

 skeletal network of the latter is much denser from a closer 

 approximation of the fibres. 



