CALCAKEA. 35 



(g) Large alate quadriradiates, lining the oscular tube. These are largest at 

 the junction with the body-wall. Basal ray straight, tapering uniformly 

 to a very sharp point. Maximum dimensions 850 /u, long x 12/a thick. 

 Paired rays bracket-shaped, equal in length, 450 fi long, oval in section, 

 16 /A deep x 6^ thick. Oral angle, 155°; folded angle, 150°. Apical 

 ray curved* orally, 100 ;u, long x 10/i, thick. 



These get smaller up to the oscular edge, where their dimensions are. as follows : 

 basal ray, 150 /a long. Paired rays, which are bent downwards, 120 ju, long 

 X 10 /A thick. Apical ray reduced to a blunt cone, 20/Along x 16/a thick. 



Subgenus GRANTIOPSIS Dendy. 



The sponge has the form of a greatly elongated hollow tube whose wall is 

 composed of two distinct layers of about equal thickness. The outer (cortical) layer 

 is provided with a very strongly developed skeleton of triradiate spicules, and is 

 penetrated by narrow ramifying incurrent canals. The inner layer is formed by 

 elongated radial chambers arranged very regularly side by side. The skeleton of the 

 inner layer is very feebly developed. The tubar skeleton is articulate and composed 

 of very abnormal sagittal triradiates, whose paired rays are greatly reduced ; the inner 

 joint of the tubar skeleton consists of chiactines. 



The above is slightly modified from Dendy's definition (7, p. 73). 



The sub-genus contains only one species. 



Grantiopsis cylindrica Dendy. 



(Plate XXXVL, Fig. 113.) 

 Grantiopsis cylindrica Dendy (7), p. 90. 



A single specimen of this species found in Australia was described by Dendy 

 (7, p. 90), who called special attention to the chiactines in its skeleton. The structure 

 of this species difiers considerably from that of the other species in the genus 

 Achramorpha, so that it seems advisable to retain the sub-genus, Grantiopsis, only 

 transferring it from the Grantiidse into the Staurorrhaphidse. 



The spicules, which have not hitherto been illustrated, are shown in Fig. 113; 

 they differ widely from any found in the new species. The sponge is fully described 

 in (7) and figured in (2). 



Megapogon. 



Staurorrhaphids in which the flagellated chambers are spherical or sac-shaped, 

 never arranged radially around the central gastral cavity, with which (or with the 

 main excurrent canals, derived therefrom) they communicate by a more or less 

 complicated excurrent canal system. The skeleton of the chamber layer is largely 



