142 OX THE REVOLUTIONS OK 



greatly extended and armed with sharp teeth ; supported on high legs, 

 the anterior extremity has an excessively elongated claw, which proba- 

 bly supported a membrane which sustained it in the air, together with 

 four other toes of ordinary size, terminated by hooked claws. One of 

 these strange animals, whose appearance would be frightful, was about 

 the size of a thrush, and the other that of a common bat ; but from 

 fragments we find that there existed a much larger species. 



A little above tliese calcareous schists is the limestone (nearly homo- 

 genous) of the ridge of Jura. It contains also bones, but always those 

 of reptiles — crocodiles and fresh- water tortoises — of which it produces 

 an abundance in the environs of Soleure. They have been there disco- 

 verd and scrutinized with much care by M. Hugi; and from the frag- 

 ments already collected we can easily recognize a considerable number 

 of the species of the fresh-water tortoise, or emydes, which ulterior dis- 

 coveries only can determine, but many of which have been already dis- 

 tinguished by their sizes and shapes from all kinds of known emydes. 

 It is among these numerous oviparous quadrupeds of all sizes and 

 forms; in the midst of these crocodiles, of these tortoises, of these 

 flying reptiles, of these immense megalosauri, of these monstrous 

 plesiosauri, that some small mammifera are said to be first detected. 

 It is certain that jaw bones, and some bones discovered in England, 

 belong to this class, and particularly to the family of didelphides, or 

 those of insectivorous animals. 



It may however be suspected, that the stones which encrust them 

 have originated from some local recomposition subsequent to the epoch 

 of the formation of these layers. However that may be, w T e find still 

 that the reptile tribe predominated exclusively for a long time. 



The ferruginous sands placed in England above the chalk, abound 

 with crocodiles, tortoises, megalosauri, and particularly with a reptile 

 which presents the singular character of using his teeth like our her- 

 bivorous mammifera. 



Mr. Mantell, of Lewes, in Sussex, discovered this peculiar animal, 

 as well as other large reptiles, in the sands beneath the chalk. * He 

 named it the iguanodon. 



In the chalk itself there are only reptilia : we find remains of tor- 

 toises and crocodile?. The famous soft sandstone quarries (carrieres 

 de tuffau) of the mountain of Saint Peter, near Maestricht, which be- 

 long to the formation of chalk, have given, beside the very large sea 

 tortoises, and a vast quantity of shells and marine zoophytes, a genus 

 of lizards not less gigantic than the megalosauri, which has become 

 famous from the researches of Camper, and by the figures which 

 Faujas has given of its bones in his historv of this mountain. 



