66 



THE TRIAS. 



lower inclination the animal had had occasion to pass only 

 in that direction, in its daily visits to the sea. Some slabs 

 similarly impressed, in the Stourton quarries, Cheshire, are 

 further marked with a shower of rain which we know to have 

 fallen afterwards, for its little hollows are impressed in the 

 footmarks also, though more slightly than on the rest of the 

 surface, the comparative hardness of a trodden place having 

 apparently prevented so deep an impression being made. 



It is in the celebrated Muschelkalk that, for the first time, we 

 find examples of a group of reptiles which have excited more 

 attention than perhaps any other extinct animals. The same 

 group, it may be remarked, occurs in the English lias and sub- 

 sequent formations : but the mere fact of writing in England 

 should not make us postpone to that place an order of beings 

 which we find earlier in another portion of what, geologically, 

 may be regarded as but one great zoological province. These 

 animals, called collectively Enaliosauria, or Marine Saurians, 

 abounded throughout a long period of the earth's history, while 

 mammalian life was yet hardly developed ; but they disap- 

 peared in what we shall have to speak of as the Cretaceous 

 Era. The Ichthyosaur, of which ten species have been dis- 



FIG. 41. 



Skeleton of Ichthyosaurus. 



tinguished, was an animal of marine habits and great bulk 

 (reaching about thirty feet in length), in which to the form of 

 the fish there were united, in a remarkable way, characters of 

 animals higher in the scale. A body, framed upon a purely 

 piscine vertebral column, containing a huge voracious stomach, 

 and terminating in a vertically expanded tail, in which respect 

 it also preserved the fish character, was furnished with the 

 head of a crocodile, and four fins approximating to the charac- 

 ter of the paddles of the whale, but composed of a greater 

 number of bones, and thus showing an affinity to the fins of 

 fishes. Over all was a skin resembling that of the cetaceous 

 animals. ISTor should it be omitted that the sternum or 

 breast-bone presents a structure resembling that of the ornitho- 

 rhynchus or duck-rat of Australia. The vast jaws of this 



