104 



ROYAI, SOCIETY OF CANADA 



P. tetranema. Suporficiul or defensive spicules veiy numerous and 1.0HK'- 

 A\lmt loii^' and slender, so as vo give a hii-suto appearance, and in flat- 

 tened specimens often to oltseure the IkmIv sitieules. Root, siny-le. stout, 

 often three inches long, with two to four slioi-t, spreading hraiiches at 

 base. Tliese terminal si)icu)e.s are flattened at the extremities. The 



Fig. 8.—Protosponffia mononema. Primary, secondary 

 and tertiarj' spicules, x 5. 



anchoring-rrd in this species is often mcreased in thickness hy a crust or 

 frosting of pyrite, and this would seem to indicate that it had, like the 

 modei-n Hyalonema, animal matter as well as silica in its composition, or 

 that foreign oi-ganic bodies attached themselves to it. 



Nearlj' as abundant as the preceding form, which it differs from in 

 the character of the anchoring-vod, each of wiiich ma}' be regarded as a 

 single elongated anchor-shaped spicule, w'ith five i-aj's. The skeleton 

 spicules are also more slender and delicate, and their rays longer, and 

 there is a greater development of protective dermal spines. The osculum 

 is narrow and Avith many long defensive needles. (Plate I., Fig. 3) 



3. — Protosponqia polynfma, Dawson. 

 (Figs. 9 and 10.) 



Fig. 9.- -Protosponi;iapolynema. Portion 

 of base of laige specimen. 



A large sponge in great 8haj)eless flattened patches, several inches in 

 diameter, though there aie smaller individuals also. Eody spicules fine 

 and slender, making a very open mesh. At base numerous simple root 



