SILURIAN ANIMALS. 



305 



usually being profusely and widely branched like most modern corals, 

 but consisting mostly of masses of parallel or nearly parallel columns. 

 In Cyatliopliijlloids (Figs. 304-306) the corals are sometimes separate 

 and of a horn-like form, and sometimes aggregated in large, rough, 



Fig. 300. 



Fig. 301. 



Fig. 302. Fig. 303. 



Figs. 298-303.— Silurian Protozoans: 298. Stromatopora concentrica. 299. Section of same. 

 300. View from above (after Hall). 301. Receptaculitis formosus (after Worthen). 302. Dia- 

 gram showing structure of Receptaculitis (after Nicholson). 303. Brachiospongia Roemerana, 

 x I (after Marsh). 



20 



