no 



ROYAL SOCIETY OF CANADA 



beds explored at Metis, and most ol' tliein have been mueli l)roken up. 

 Only one specimen was obtained in a tolerable state of conijileteness. 



For further remarks on the structure and affinities of this sponge by 

 Dr. Hinde, see the paper of 1889. 



(Ienus ACANTHODICTVA. Hiiule. 



Sponges ap])roxiniately sulicyliudrical in lorm, consisting of a skeletal 

 mesh-work of longitudinal and transverse spicular strands or tibres. The 

 longitudinal strands are composed of somcAvhat loosely arranged fascicles 

 of elongated overlapping spicules, and the spicules of the slender trans- 

 vei*se fibres are as a rule disposed in a single series. From the outer 

 surface of the sponge, numerous spicular rays project outwards ut right 

 angles. The sponge appears to have been anchored by a basal prolong- 

 ation of the longitudinal strands. Owing to the pi'csent com])r(\ssed 

 condition of the specimens it is ditîicull to determine the oi-iginal form 

 of the constituent spicules. 8ome of the elongated longitudinal 8])icules 

 may be merel}^ simple I'od-like forms, othei-s are clearly cruciforjn and 

 their transverse rays form the crosstibi-es. The spicular rays of the 

 projecting bristles of the surface may be the free distal rays of normal 

 hexactinellid spicules, but only these ])rojecting rays can now be clearly 

 distinguished ; the others are merged in the longitudinal fascicles. 



The general structure of the skeleton resembles that of Cyathophycus, 

 Walcott, but it is characterized by the pi-esence of the projecting surface 

 rays. The mesh is also of a looser character than in Cyathophycus and 

 its arrangement in quadrate areas is only faintly recognisable. 



!i. — AcANTHODicTYA Hrsi'iDA, Hinde. 

 (Figs. 20 and 21. PI. 111., Fig. 11.) 



^ 



Fig. 2l.—Acant}iu(Jic/;/a hispidii. -^Fortionn enlarged x 5, 



sliowiiiK fnunevvork and cruciform and 



protective spicules. 



Ft(J. 20.~Acantho'lictya 

 hispida. Restored. 



