TKTRAXONIDA. 11 



('is \. MVI:\ vi n \ M 



(Plate X., figs. 15, 16. Plate XI.-, figs. 1-3.) 

 1907. Cinafhyra rtrtn Leodenfcld (lla. p. 310). 



Two small specimens of this species, obtained from deep water (130 fins.). 

 show a remarkable variation in the porocalyces and oscules. The porocalyces instead 

 of being situated below the general surface are elevated altove it in the form of 

 rounded warts or monticules alxmt 1 mm. in height ; the oscules likewise form 

 small cylindrical chimneys about 2 mm. in height. 



The larger of the two specimens is 3*5 x 2*5 cm. in its diameters, not including 

 the root-tuft, which is about 2 cm. in thickness. A large part of the surface is covered 

 with the little porocalycal monticules, and at one end are several oscular chimneys. 

 Situated at a varying height on each monticule is a semiluuar slit which opens into 

 a caeca 1 fold or pocket that has been formed by the upward growtli and protrusion 

 of the monticule ; when the lip is near the summit of the monticule, it surrounds the 

 latter like a kind of prapuce. The pore-perforated floor of the porocalyx itself is, 

 in every instance, closely folded with longitudinal pleats which, however, can l>e unfolded. 

 The summit of the monticule is formed by the tops of these folds, and bundles of the 

 hlspidating trichodal protriaenes can occasionally be seen projecting from the summit. 

 The long slender bundles of protriaenes divide into two layers at the inferior proximal 

 edge of the semilunar fold, one set being in the fold iteelf and extending to the edge 

 of the same and sometimes a little beyond, the other set passing up in to the floor and 

 walls of the porocalyx iteelf. The edge of the semilunar lip is provided with a Iwnd 

 of myocytes. This curious variation appears to have taken place as an adaptation 

 necessitated by the spiral mode of growth of the sponge ; if such growth l>ecame 

 excessive the porocalyces would be in danger of becoming closed altogether from one 

 lip of the orifice overlaying the other. 



Locality. Winter Quarters. No. 10 Hole, 130 fms. 



II. GRADE MONAXONELLIDA, DENDY. 



There are, in all, forty-three species belonging to this group. Of these, eight 

 belong to the Astromonaxinellida, and thirty-five to the Sigmatomonaxiuellida. 

 Twenty-two species are new, and there are, in addition, seven new varieties of species 

 already described. There are four new genera, of which one l>elongs to the Axinellidae, 

 two to the Myctilinae, and a fourth, Pylodenna (Renierinae), has l>een established to 

 receive Halichondria latrunculioidex Ridley and Dendy. 



New and interesting forms of xpicule-t. The new Mycaline genus Cercidochela is 

 characterised by the possession of remarkable modified isochelae, which I have termed 

 canonchelae (I.e., shuttle-shaped chelae). In them the single central teeth from each 

 end have fused, so that a complete shuttle-shaped spicule results, recalling the melon- 



