THE PRE-ADAMITE EARTH. 



the 56, or over the immense extent of 90 of latitude, being a 

 quarter of the terrestrial globe. In longitude this subsidence 

 was not less extensive, and is assigned by M. D'Orbigny as the 

 immediate cause which terminated the fifth Cretaceous period. 



SIXTH CllETACEOL'S PEKIOD. 



442. The sixth Cretaceous stage corresponds with the tenth or 

 upper white-chalk group of Lyell, including the white chalk with 

 flints of the north and south downs. It is identical with the 

 strata called by the Italians la Scaglia. 



443. A generic summary of the fauna is given in the following 

 table : 



Synopsis of the Animal Kinr/dom (exclusive of Annul at a) during the 

 Sixth Cretaceous Period. 



Adding two genera of Crustacea not included in this table,' it 

 appears that the fauna hitherto discovered consisted of 305 

 genera, of which 81 were new, 

 periods. 



and 224 revived from former 



112 



