CHAP. XXXV.] FOSSIL CORAL REEF. 209 



a group of these ancient corals, and, in the other window, a set 

 of recent corals from the West Indian seas, of the genera Mean- 

 drina, Astrea, Madrepora, and others ; some of them as heavy 

 and stony as those of older date, their pores, foramina, and 

 minute microscopic structure, not being more distinctly preserved. 

 No one but a zoologist would have been able to guess which set 

 were of modern, and which of ancient origin. Yet so old are 

 the fossils, that they are referable to an era antecedent to the 

 Alleghanies, the Alps, and the Pyrenees, nay, even to the time 

 when by far the greater part of the materials composing these 

 mountain-chains were slowly elaborated beneath the ocean. 



