i 



the vanes as well as the shafts are preserved. It differs 

 from all existing birds in its long tail, consisting of 

 twenty vertebra?, each of which supports a pair of 

 quill feathers. From the form of the tail, the animal 

 was at first regarded as an intermediate state between 

 a bird and a reptile, until Professor Owen showed that 

 it had no reptilian character. Professor Prestwich has 

 recently discovered in the Kimmeridge Clay the 

 gigantic reptilian Iguanodon, or some closely allied 

 Dinosaur, which has hitherto been thought to have 

 browsed only on the trees and herbs of the wealden 

 and lower cretaceous forests, proving a con- 

 tinuity of land-condition from the upper oolite to the 

 lower greensand period. We now arrive at a very 

 important era of plant-life, namely y the first appear- 

 ance of dicotyledonous plants, not only in abundance, 

 but in great varieties of forms. Unknown before, they 

 rapidly prevailed, compelling the cycads and conifers 

 to decrease and abandon their hitherto dominant posi- 

 tion. The cretaceous fresh-water deposits of Bohemia 

 are rich in fossil-plants, as also those of Moravia, 

 Harz, Saxony, Westphalia ; the neighbourhood of Aix- 

 la-Chapelle and of Toulon, have furnished a consider- 

 able series of fossil-plants from the middle-chalk, which 

 seem to have grown near the shores of a cretaceous 

 sea. They present a curious assemblage of extinct 

 genera, with some which now only grow within the 

 tropics, and others which are confined to northern Europe. 

 The genus Credneria is an example of the first (now 

 only found in a fossil state) ; while Hymenoece^ 



