570 



THE WONDERS OF GEOLOGY. Lect. V. 



are spread out and united together. Thus in the delicate 

 and agile form of the Serpent, and in the heavy and torpid 

 mass of the Turtle, the same general principle of structure 

 prevails, and by a simple modification, the skeleton is 

 adapted for beings of very dissimilar forms and habits. The 

 Testudinata, or turtles, like the other large reptiles, are 

 essentially confined to torrid and temperate regions. The 

 fresh-water species are capable of bearing a higher lati- 

 tude than the terrestrial : upon the whole the utmost range 

 of this order appears to be from 54° N. lat. to about 

 40° S. lat.* The fiuviatile species, or JEmydes, are carnivo- 

 rous, feeding on frogs and small animals ; those of the genus 

 Trionyx {three claws) are African or Asiatic; with the 

 exception of the Trionyx ferox y which inhabits the hot 

 regions of America. They live upon food which is found 

 at the bottoms of rivers ; in the stomachs of several pro- 

 cured from the Ganges, by Col. Sykes, were large quantities 

 of mussels, the shells of which were broken into small 

 angular fragments. I have fossil bones of a Trionyx 

 (T. Bakewelli) from Tilgate Forest, imbedded in a mass of 

 mussel shells ; a collocation which might be expected in a 

 fiuviatile deposit. The form of the ribs and other parts of 

 the skeleton, differs in the land, river, and marine Turtles, 

 so that the fossil bones can, for the most part, be readily 

 referred to the respective groups. 



Fossil Turtles. — The earliest indications of the existence 

 of reptiles on the surface of our planet were supposed to be 

 those of Chelonians ; the imprints of the feet or pats 

 apparently of a land tortoise, occurring on slabs of Triassic 

 sandstone in Dumfriesshire (ante, p. 555) ; but recent dis- 

 coveries afford glimpses of a more ancient race of batrachians, 

 and of lizards, even as low down in the geological scale 



* On the Testudinata, by Thomas Bell, Esq. 1 vol. folio ; one of the 

 most splendid works on Natural History that has appeared in this 

 country. 



