206 ROYAL SOCIETY OF CANADA 



directed outward. The spicules of the outer surface are the same as 

 those of the tubar siicleton ; those which make up the ridges have their 

 basal rays pointetl outward, but those occupying the surface of the sunken 

 areas between the ridges have their basal rays directed inward instead of 

 outward. Quadriradiates are present in the gastral surface. Stout oxeote 

 S])icules proceed from the ridges far beyond the outer surface ; their 

 inner ends frequently penetrate deeply into the wall of the sponge. 



Sjx'cules. — (1) Tn'radiates, of the tubar skeleton and of the dermal 

 surface, with gradually and sharply pointed rays ; the basal ray is 

 straight, up to 0'lt)4- mm. long and 0-00'.) mm. thick at the base ; the 

 lateral rays are generally slightly curved and about 010!) mm. long 

 (Plate II., tig. Sa). (2) Quadn'radiates, of the gastral surface, with 

 short, stout, apical rays which project beyond the gastral surface and 

 are curved slightl}* toward the o.sculum ; the facial rays are long, sharply 

 pointed, up to 0'0Î>8 mm. long and O-OOtj mm. thick at the base ; the 

 apical rays vary in length from 0026 to 00(J5 mm. and in thickness from 

 0-006 to 0-013 mm. (Plate 11.. tig. 8è). (3) Oxeote spicules, of the 

 dermal surface, stout, obtusely but shar])ly pointed, up to 1-15 by 0-205 

 mm. in size ; the proximal end is generally stouter than the distal end 

 (Plate II., tig. 8e). The oxeote spicules surrounding the oscular open- 

 ing are almost thi' sami' in size as those of the dermal surface ; their 

 average thickness is 0013 mm. 



Locdlitjj. — Eight miles southeast of Bonaventure Island, (iaspé, 

 in 56 fathoms, .stones and coarse sand, one specimen, in alcohol, J. F. 

 Whiteeaves. 1S72. 



CtRAN'TIA ('ANADENSrS. (Sp. UOV.) 



(Plate 111., tigs. 7, l<t. nb, 1c.) 



Sponge small, tubular, erect, attached by its base to an alga ; it is 14 

 mm. long, nearly 3 mm. broad a little below raid-height and contracted 

 slightly near the upper end whcic it terminates in an osculum, 1 mm. 

 wide, which is ]»roteeted by a fringe of linear spicules. A gastral 

 cavity about 1 mm. in width extends the entire length of the sponge and 

 ends above in the osculum. Colour, inspirit, pale brownish-red.' Tex- 

 ture, tirm, compact. Surfd'-e^ even, slightly hispid. 



Skeleton. — The wall of the sponge is 1 mm. thick and is traversed 

 l»y radial tubes about 0082 mm. wide. The tubar skeleton is articulated 

 and comi)osc'd of triradiate s|)icules having their basal rays directed out- 

 ward. A cortical layer of triradiate spicules, similar in form and size to 

 those of the tubar skeleton, lies immediately beneath a thin dermal 

 membrane which is pierced by numerous minute pores, averaging 0030 

 mm. in width. The gastral surface is supported by quadriradiate spicules 

 whcse apical raj's project into the gastral cavity. Stout oxeote spicules 



' The colour is vory prol>al)ly influenced by the red mud of the bottom derived 

 from the brick-coloured rocks of Prince Edward Island. 



