30 FOSSIL MAMMALIA. 



bones, found in the ferruginous sandstone of Tilgate-Forest, in 

 Sussex, the Doctor calculates that the animal in question could 

 not have been less than from sixty to seventy feet in length. 

 Remains of this reptile, or at least of species referrible only to 

 this genus, have been also discovered in France and Ger- 

 many, in the calcareous slate above the oolitic beds. 



In this same slate, the long-beaked crocodiles continue to 

 abound ; but the most remarkable animals there are the ptero- 

 dactyls, or flying-hzards. They appear to have been sustained 

 in the air, on the same principle as the cheiroptera : they had 

 long jaws, armed with trenchant teeth, hooked claws ; and some 

 species, as would seem from the fragments remaining, arrived 

 at a considerable size. 



In the nearly-homogeneous limestone of the crests of Jura, 

 a little higher than the calcareous slate, are bones, but invari- 

 ably of the reptile class. There are crocodiles, but more espe- 

 cially fresh-water tortoises, as yet not fully determined, but 

 many of which, by their magnitude and conformation, are 

 strongly distinguished from all known species. 



Amid those innumerable reptiles, whose varied structure and 

 colossal dimensions rival, if not surpass, the fabled monsters 

 of poetical antiquity, we begin, as is said for the first time, 

 to recognise the remains of some small mammalia. Jaws and 

 bones have been discovered in England, appertaining to the 

 families of the didelphis and insectivora, in these situations. 

 But if the locale of Dr. Buckland's discovery of the opossum 

 before-mentioned be completely established, it must be granted 

 that they appear sooner. Cuvier, however, seems to think 

 that the rocks in which the bones in question are incrusted 

 may owe their existence to some local recomposition, posterior 

 to the era of the original formation of these strata ; and it is 

 most certain that, even for a period considerably subsequent, the 

 reptile class exclusively predominate. In the ferruginous sands 

 above the chalk in England, abundance of those already enume- 

 rated occur ; and an additional reptile has been discovered there 



