Professor Owen on British Fo^aU Bepdles. 6d 



are marine species, and are equally distinct, with the lacer- 

 tians, from those of the super-imposed tertiary beds. 



The most interesting fact which the palteontology of the 

 cretaceous period has yielded, with reference to the great 

 saurian division of the class of reptiles, is the commencement, 

 or rather the last appearance of the fossil remains of an order 

 of reptiles (^Enaliosauria) now altogether extinct. 1 have ex- 

 axamined portions of the lower jaw with teeth of a large spe- 

 cies of Ichthyosaurus from the lower chalk between Folkstono 

 and Dover, which is very closely allied to, if not identical with, 

 the Ichthyosaurus communis. The femur of a large Plesiosau- 

 rus has been obtained from the chalk of Shakspeare's Cliff. 

 Remains of more than one species of plesiosaurus occur in the 

 gault, and are associated with the ichthyosaurus in the green- 

 sand near Cambridge, and in the Kentish Rag near Maid- 

 stone. 



In the green-sand also we first meet with evidences of rep- 

 tiles exhibiting modifications of structure, especially of the 

 locomotive extremities, as remarkable and as different from 

 those of existing species as are presented by the Enaliosauria, 

 bat pointing as strongly to an adaptation for terrestrial life as 

 does the enaliosaurian structure to aquatic existence. The 

 specimen of the unquestionably teiTestrial saurian here alluded 

 to, viz., the Iguanodon^ is the more remarkable in the subcre- 

 taceous marine strata, in consequence of its presenting the 

 largest portion of the connected skeleton of the same indi- 

 vidual of this species that has hitherto been found. 



Gigantic crocodilian reptiles, removed by generic modifica- 

 tions of structure from the eocene and existing crocodiles, 

 now likewise begin to be indicated, as by the teeth of the Po- 

 lyptychodon from the green-sand quarry at Maidstone, and 

 by the large bones of the extremities from the quarries of a 

 corresponding stratum at Hythe. 



The chelonian from the greensand (Chelone pulchriceps) dif- 

 fers from the eocene and all existing turtles in a very interest- 

 ing modification of the anatomy of the cranium. 



In the Wealden group of fresh-water strata, the Enaliosau- 

 rian order continues to be represented by the Plesiosaurus^ but 

 no remains of the more strictly marine genus, Ichthyosaurus ^ 



