10 R. KIRKPATEICK. 



(5) Trichodal protriaenes with rhabdome 550 fi in length, and with longest 

 cladus 50 fi. 



Microscleres. (6) Sigmata, 18"36/x in length, 1*8 /x in thickness, and 10'5/iin 

 breadth in the C-aspect ; surface finely granular. 



There are twenty-five specimens of this sponge, the largest being 10 "5 X 8 cm. 

 and the smallest 8x6 mm. The salient external features of the larger specimens 

 are the spiral series of conules and tufts wrapping round the sponge, and the porocalyces 

 obliquely displaced by the spiral growth of the sponge. The root-tuft is often much 

 more bulky than the sponge body. The conules which form a fleshy basal sheath to 

 the spicular tufts attain a height of 5 mm., and the tufts of an additional 10 mm. 

 The porocalyces have an average diameter of about 4 mm., the oscules being about 

 •5mm. in the contracted state; the latter have a fine marginal fringe of small' 

 protriaenes. 



On section, the flesh is reddish in colour ; the cortex indiscernible and can be 

 peeled off in the form of a thin skin, its thickness being about 30 mm. ; the outer 

 third is formed of large rounded coUencytes, 18/i in diameter, full of granules, 

 which stain deeply. Covering the outer surface of the sponge is a well-defined 

 layer of sigmaspires : a layer of the same spicules also lines the surface of 

 the canals. 



Canal System. Currents pass through the pores in the porocalyces to large 

 sub-dermal spaces leading to one large inhalant canal. 



The flagellated chambers are eurypylous. PI. X. fig. 5 shows numerous apopyles 

 opening into a commencing exhalant canal. 



The collar-cells (X. 6) here have their collars concrescent. 



Numerous ova are present in some of the specimets, and in various stages — but 

 not in the same specimen — some having pseudopodia-like processes, others being 

 spheroidal and devoid of processes. In one unstained section in balsam the large 

 spherical ova are 330 /x in diameter, with nucleus 50 /x, and nuclecdus 9 * 75 /x in diam'eter ; 

 here the ova can be seen with the naked eye as deep yellow spots, and with a hand 

 lens the clear nucleus can be distinctly made out. 



Young specimens. In early stages there is no root-tuft, but in a series of small 

 specimens, the conule tufts can be seen to lengthen at the narrow end of the specimen 

 till they form a root-tuft. At first there is only one porocalyx situated on one side, 

 and a single oscule, surrounded by a fringe of protriaenes, a little below and behind 

 the broad end of the egg-shaped specimen. One small specimen (No. 264, 13, ii. 04) 

 differs from the others in having long tufts each with a long fleshy base, the tufts 

 all pointing downwards from the flat upper end ; a few small contracted porocalyces 

 are concealed in the axils of the fleshy conules. 



Localities. Winter Quarters. Twenty-five specimens were obtained from ten 

 localities, and from depths varying from 10-30 fathoms. 



