§ 32. ZOOPHYTES OF THE CHALK. 635 



there are numerous existing species of corals, with many 

 extinct, or unknown as natives of the adjacent seas. The 

 miocene of North America contain many kinds of polyparia, 

 some of which appear to be peculiar to those strata.* In 

 the eocene deposits there are several extinct genera and 

 many species, associated with some living forms. In the 

 Chalk formation corals are locally abundant, in the sandy 

 and argillaceous strata (as at Maestricht) ; but throughout 

 vast areas of the fine white chalk, there are no considerable 

 beds of corals, nor appearance of coral reefs : the species 

 are, for the most part, small and delicate (ante. p. 319). 



The manner in which the remains of polyparia are dis- 

 tributed in the white chalk involves an interesting inquiry ; 

 they occur promiscuously intermingled with shells, echini, 

 and fishes ; we find no beds of corals — nothing to point out 

 the former existence of reefs. This phenomenon, however, 

 is in accordance with the general lithological character of 

 the Chalk formation, and the nature of its organic remains ; 

 both of which indicate a profound ocean. As polyparia can 

 only exist at moderate depths, the occurrence of coral reefs 

 was not to be expected, except in those areas which may be 

 supposed to have been formed in the shallows, or near the 

 sea-shores. 



In the Danish islands of Seeland and Moen, the flinty 

 chalk is covered by coral limestone, some portions of which 

 form a compact building-stone, while others are mere masses 

 of coral cemented together by a white detritus. These beds 

 belong to the chalk formation, for although they abound in 

 univalve shells not common in our cretaceous strata, yet a 

 large proportion of the sponges, corals, echinites, and 

 belemnites, are identical with those of the English Chalk. 

 Mr. Lyell therefore infers, " that the peculiarity of the fossil 



* See report on Corals from the Tertiary Formations of North 

 America, by Mr. Lonsdale ; Geol. Journal, vol. i. p. 495. 



