THEORY OF THE EARTH. 261 



But the most remarkable animals which these 

 limestone slates contain, are the flying lizards, 

 which I have named Pterodactyli. 



They are reptiles whose principal characters 

 are, a very short tail, a very long neck, the muzzle 

 much elongated, and armed with sharp teeth ; the 

 legs also long, and one of the toes of the anterior 

 extremity excessively elongated, having prohably 

 served for the attachment of a membrane adapted 

 for supporting them in the air, accompanied with 

 four other toes of ordinary size, terminated by 

 hooked claws. One of these strange animals, 

 whose appearance would be frightful did they oc- 

 cur alive at the present day, may have been of 

 the size of a thrush*, the other of that of a com- 

 mon batf ; but it would appear from some frag- 

 ments that larger species had existed J. 



A little above the limestone slates is found 

 the nearly homogeneous limestone of the Jura 

 ridges. It also contains bones, but always of 

 reptiles, crocodiles, and fresh-water tortoises, of 

 which a vast quantity is found in particular 

 in the neighbourhood of Soleure. They have 

 been very carefully searched for by M. Hugi ; 

 and, from the fragments which he has already 



* Researches, vol. v. part ii. p. 358. et seq. 

 t Ibid. p. 376. J Ibid. p. 380. 



