148 



HISTORICAL PALAEONTOLOGY. 



great number of the remains of Sea-mosses (Polysoa). Some 

 of these belong to the ancient type Ptilodictya, which seems tc 



Fig. 91. Fragment of 

 Ceriopora Hamiltonensls, 

 of the natural size and 

 Fig. 90. Fragment of Clathopora intertexta, of the enlarged. Devonian, Cana- 

 natural size and enlarged. Devonian, Canada. (Original.) da. (Original.) 



disappear here, or to the allied Clathropora (fig. 90), with its 

 fenestrated and reticulated fronds. We meet also with the 

 graceful and delicate stems of Ceriopora (fig. 91). 



Fig. 92. Fragment of Fenestella magnified, 

 of the natural size and enlarged. Devonian, 

 Canada. (Original.) 



Fig. 93. Fragment of Retepora 

 Phillipai, of, the natural size and 

 enlarged. Devonian, Canada. (Orig- 

 inal.) 



Fig. 94. Fragment of Fenettella 

 cribrosa, of the natural size and en- 

 larged. Devonian,Canada. (Original.) 



The majority of the Devonian Polyzoa belong, however, to 

 the great and important Palaeozoic group of the Lace-corals 

 (Fenestella, figs. 92 and 94, Retepora, fig. 93, Polypora, and 



