m» 



104 



ROYAL SOCIETY OF CANADA 



P. tcfrtinema. Superficial or del'onsive spicules very numerous and some- 

 what long and slender, so as to give a liirsute appearance, and in flat- 

 tened specimens often to obscure the body sjiicules. Eoot, single, stout, 

 often three inches lonj,;, witli two to four short, spreading branches at 

 base. These terminal spicules are flattened at the extremities. The 



Fig. 8. -Pi'otosponffia mononema. Primary, secondary 

 and tertiary spicules, x n. 



anchoring-rod in tliis species is often increased in thickness by a crust or 

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

 modern Hyalonema, animal matter as well as silica in its composition, or 

 that foreign organic bodies attached themselves to it. 



Nearly as abundant as the preceding form, wliich it differs from in 

 the character of the anchoring-rod. each of which may be regarded as a 

 single elongated anchor-shaped spicule, with five rays. The skeleton 

 Bpicules ai-e also more slender and delicate, and their rays longer, and 

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

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



3. — Protosi'ongia polynema, Dawson. 

 (P^igs. !» and 10.) 



Fig. 9. — Protonponqia polynema. Portion 

 of base of large specimen. 



A large sponge in great shapeless flattened patches, boveral inches in 

 diameter, though there are smaller individuals also. Body spicules fine 

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



