REPTILES ABUNDANT. 57 



been, like those of the kangaroo and some other genera, much 

 smaller than the hinder, some specimens of which measure 

 eight inches by five. These batrachia present affinities to 

 the fish class in their biconcave vertebrae and the formation 

 and arrangement of the teeth. Their nostrils being also, like 

 those of the Sauria, placed near the extremity of the head, 

 indicate a partially marine habitat, such an arrangement 

 being required to enable the animal to breathe while nearly 

 altogether sunk in the water. 



Quarries of the red sandstone of this system also present 

 an abundance of footmarks attributed to tortoises, thus point- 

 ing to the contemporaneous existence of a third order of rep- 

 tiles, the Chelonia. The first examples were discovered by 

 the Rev. Dr. Duncan in the quarry of Corncockle Muir, Dum- 

 friesshire, where the slabs incline at an angle of thirty-eight 

 degrees, and the footmarks are distinctly traced up and down 

 the slope, as if, when the surfaces w r ere those of a beach at, 

 however, a 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 fossil animals. The 

 same group, it may be remarked, occurs in the English lias 

 and subsequent 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 de- 

 veloped ; but they disappeared in what we shall have to speak 

 of as the Cretaceous Era. The Ichthyosaur, of which ten 



