278 FOSSIL REPTILES. 



in general, but more especially in the sea-tortoises, to a greater 

 or less- advanced age. 



Accordingly, it is impossible to believe that the test<E, or 

 carapaces, represented in M. St. Fond's "History of the 

 Mountain of St. Pierre," indicate a new genus. They exhibit 

 no part which does not exist in the testce of all tortoises, or 

 nothing which does not resemble the sea-tortoises in general. 



M. St. Fond was also desirous to estabhsh another genus, 

 or at all events a new and unknown species, on some other 

 remains, found in the same mountain, but apparently with as 

 little foundation as in the instance just cited. This, however, 

 was entirely established on mutilated specimens. 



At all events, it is quite certain that the tortoises of Maes- 

 tricht bear the generic character of the sea-tortoises, or Chelo- 

 nian reptiles ; and it is equally certain that they appertain to a 

 species very different from all existing sea-tortoises. They 

 have the ribs ossified scarcely for one-third of their length ; 

 whereas any of the existing species of similar size would have 

 them ossified almost to the end. It is, however, observable, 

 that in these tortoises, as in others, the progress of ossification 

 is in proportion to age. 



Near Glaris, in the mountain called Plattenberg, is a slate- 

 quarry, with strata inchning to the south, which is very abun- 

 dant in impressions of various kinds of fish, and in which some 

 remains of tortoise appear to have been found. Those who 

 endeavoured to determine the species took these for the re- 

 mains of our common emys, or fresh-water tortoise (testudo 

 Europaa.) Thus was it named by Andreae, who observes, that 

 these animals formerly existed in the lakes of Switzerland ; 

 just as if the formation of the slate-mountains could have any- 

 thing in common with the present lakes of that country. 



There can be no doubt, as M. Cuvier observes, that the tor- 

 toise in question belongs to the marine sub-genus. A decisive 

 proof of this is the elongation, and more especially the unequal 

 elongation, of the toes. In the fresh- water tortoises the toes 



