146 



HISTORICAL PALEONTOLOGY. 



fan-like or funnel-shaped form, which grew attached by its 

 base to some foreign body. The frond consists of slightly- 



a 



Fig. 90. Fragment of Clnthropora interiexta, of the 

 natura 1 size and enlarged. Devonian, Canada. (Original.) 



Fig. 91. Fragment of 

 Ceriopora. H amiltonensis, of 

 the natural size and enlarg- 

 ed. Devonian, Canada. (Ori- 

 ginal.) 



diverging or nearly parallel branches, which are either united 

 by delicate cross-bars, or which bend alternately from side to 

 side, and become directly united with one another at short 

 intervals in either case giving origin to numerous oval or 



L. 



F'g. 92. Fragment of Fenestella magn : fica, 

 of the natural size and enlarged. Devonian, 

 Canada. (Original.) 



Fig. 93. Fragment of Retcpora 

 Phillips!, of the natural size and 

 enlarged. Devonian, Canada. (Ori- 

 ginal.) 



Fig. 94. Fragment of Fenestella 

 cribr<"-a, of the natural size and enlarg- 

 ed. Devonian, Canada. (Original.) 



oblong perforations, which communicate to the whole plant- 

 like colony a characteristic netted and lace-like appearance. 

 On one of its surfaces sometimes the internal, sometimes the 

 external the frond carries a number of minute chambers or 



