Tabulate Corals with existing Species. 189 
generalization, he extended it likewise to the extinct “ Rugosa” 
or Cyathophylloid corals,* at first apparently with some hesita- 
tion, but more recently without qualification.t 
rom this conclusion, if admitted, it followed that in the 
Paleozoic ages there were few, if any, true polyp-corals, but, on 
the other hand, the class of Acalephs was abundantly repre- 
sented by a great variety of coral-making forms, some of them 
of great size, and capable of building extensive coral-reefs, 
similar to those made by true polyp-corals in modern times! 
Thus the geological importance of these two classes of animals 
would be completely reversed, as well as our ideas of the nature 
of corals and coral-reefs. 
These views have been held and advanced by Professor 
gassiz for many years, and have been urged quite recently, 
notwithstanding the great amount of evidence that has been 
3 contributions to the Natural History of the United States, vol. iii, pp. 61-3, 
and vol. iv, pp. 292-6, and p. 338. : 
+Bulletin of the Museum of Comparative Zodlogy, vol. i, No. 13, p. $84, 1870. 
‘ 
