REPORT ON THE CALCAREA. 39 



as long as thick), cylindrical, with rounded ends ; the basal ray is sometimes rather 

 longer than the lateral ; some of them show an incipient fourth apical ray. 

 The sagittal triradiate spicules are on an average of the same size as the regular ; their rays, 

 compared with those of the latter, are more conical, although there is no want of 

 intermediate stages. They are inconstant in their outlines. With some of them the 

 irregularity consists only in their not being flat, the point of meeting of the rays not 

 lying in the same plane as their ends, the basal ray being in this case either of the 

 length of the lateral rays or rather longer ; but such a form is comparatively rare. The 

 greater part also show variation in their angles, the angle formed by the basal and each of 

 the lateral rays varying from 120° to 92° ; the length of the basal ray is in this case 

 variable (0'12 to 025 mm.) ; it is either straight or undulating, the lateral rays being horn- 

 shaped, and curved more or less one towards the other. 



There exists also on the outer surface of the colony another constituent part of the 

 dermal set, namely, large regular triradiate spicules, each ray attaining a length of 0'8 

 mm., and a diameter of O06 mm.; but these spicules are so extremely rare, that they are of no 

 consequence for systematic purposes. 



Colour. — Yellowish. 



Habitat.— Station 186, September 8, 1874; lat. 10° 30' S., long. 142° 18' E. ; 

 Cape York, Australia ; depth, 8 fathoms ; coral sand. 



Order HETEROCXELA, Polejaeff. 



Calcarea with separate flagellated chambers lined with flagellated cells, the remaining 

 parts of the inner surface being covered with pavement-epithelium. 



Family Syconid^e (Sycones), Hseckel. 



Heteroccela whose large cylindrical flagellated chambers (tubi radiates, auctorum), 

 show a radial disposition with respect to the central cavity, communicating with it 

 directly without the mediation of any exhalent canals. 



Sycon, Risso. 



Syconidae with articulated tubar skeleton, with radial tubes either quite free or, if 

 grown together, united in such a manner that the individuality of every tube may be 

 easily discerned, owing to the absence of any independent cortex. 



