270 



bone of a tortoise for the horn of a stag; fragments of the sternal plates 

 (plastrons) of a tortoise for the branched part of the horns of the elk ; 

 and two bones of the carpus, belonging also to the tortoise, for the pubis 

 and the clavicle of a crocodile. Similar remains to those found by Mr. 

 Johnson, are sometimes found in the Stansfield lime-stone. 



Plate XVIII. Fig. 3, is the fossil head of a tortoise, found at Shepey 

 by Mr. Crow. 



The necessity of ascertaining the number of existing species of the 

 crocodile, and of pointing out their distinctive characters, previous to the 

 examination of their fossil remains, must be obvious ; and that this task 

 has been performed by M. Cuivier, who possesses abilities arid oppor- 

 tunities so well fitted for the undertaking, is a circumstance which has 

 considerably promoted the advancement of our knowledge in our fa- 

 vourite science. The gratitude due to him, on the present occasion, is 

 considerably augmented by the consideration, that at the period at which 

 his investigations were made, almost every one who had written on 

 the subject had unfortunately contributed, by their errors, to envelope 

 the subject in confusion. M. Schneider, however, had sedulously em- 

 ployed himself, and with some success, in makjng some useful and 

 important distinctions, with respect to these animals ; Histoire des Am- 

 phibies, cap. n. But the most instructive labours were those of M. 

 Geoffroy, who not only made some important anatomical researches on 

 the crocodile of the Nile, but also on the crocodile of St. Domingo, 

 which bore so strong a resemblance to that of the Nile, as to have led to 

 the suspicion that they were both of the same species ; and, of course, 

 to a doubt as to the circumstance dwelt on by Buffon, that no species 

 belonging to the torrid zone had been primitively in both continents. 

 The observations, however, of M. Gregoire, determined that the croco- 

 dile of St. Domingo deserved to be regarded as of a different species from 

 that of the Nile. Ann. du Mus. Nat. T, i. p. 37 and 53. 



This same naturalist suspected, from the accounts he had received, 

 that two distinct species of the crocodile existed in Egypt; one of these 



