137 



world. In no age before or since, not even at the present time, 

 have Coral reefs of greater extent been formed. Favosites 

 Goldfwsii; Cyathophyllum rugosum, Zaphrentis Rafinesquvi ; 

 Syringopora Maclurii and Aulopora cornuta, were some of the 

 reef-building Corals of this period, and these denizens of the 

 ancient reef are weathered out to perfection on the horizontal 

 ledges of the rock. When the water is low, the softer portions 

 of the matrix having been removed, and the mud of the reef 

 cleared away by the running water, the Corals stand out in 

 rehef, in aU their pristine beauty, with their branching stems 

 or massive coraUums, as when living in the lagoons of the 

 Devonian sea. 



In Canada, the Devonian rocks, according to Sir William 

 Logan, attain a thickness of 7000 feet, and contain extensive 

 beds- of Coralligenous Limestones, having a reef-Hke character 

 simUar to those described. Sir William informed me, in the 

 Exhibition of 1862, when shewing the oil obtained from the 

 Devonian Coral rocks of Canada, that he was of opinion much 

 of this oil had an animal origin, and was derived from the 

 reef-building Polyps that Hved in the Devonian period. 



The Devonian Corals aU belong to the same groups as those 

 of the Silurian period. The species, however, are distinct, 

 although the general fades of the fauna has a strong family 

 resemblance. The Zoantharia apokosa are absent, and the 

 ZoANTHABiA PERFORATA is represented by a single doubtful form 

 the genus Pleurodydiwm. 



The ZoANTHARiA TABTJLATA are very abundant ; they belong 

 to the families Milleporid^, Favositid^, and Seriatopobid^. 



MiLLEPORID-j; 



Heliolites 

 Plasmopora 



Favosites 



Emmonsia 



Rcemeria 



Michelinia 



Alveolitis 



Chcetetes 



Favositid-e 



Battershya 



Monticulipora 



Beaumoiitia 



Syringopora 



Thecostegites 



Chonostegites 



