OF CREATION. 279 



smooth skin, slender tail, and no defensive weapons. 

 It presents so many analogies with the torpedo, that, 

 like the species of that singular group, it may have heen 

 provided with a special electric apparatus, to enable 

 it to obtain food and resist the attacks of its enemies. 



We ought not to conclude the account of the fishes 

 of this period without referring also to those species 

 of the Ganoid and Placoid orders found in the isle 

 of Sheppey. The hard crushing teeth of some re- 

 markable Granoid fishes are found occasionally, and 

 have been described by M. Agassiz, in his great work 

 on fossil fishes. The flat pavement of palatal bones 

 with which these animals were provided probably 

 enabled them to grind to powder the shells of the 

 molluscs and crustaceans on which they fed. Besides 

 this group, there was also a species of sturgeon ex- 

 isting at the period in question ; as many as seventeen 

 well-marked species of large rays, besides two saw- 

 fishes ; ten species of shark, and three species of the 

 family of CMmarida or sea-monsters, which exhibit 

 a close affinity to the sharks. 



The reptiles inhabiting the land, and the rivers and 

 estuaries near land, at the time of the London clay 

 deposit, exhibit evidence with regard to the question 

 of climate strictly in accordance with that suggested 

 by the examination of the fishes, the molluscs, and 

 the vegetables. Thus we find a lacertian and several 

 crocodilian animals, some turtles and tortoises, and 

 a very interesting addition to previously discovered 

 reptiles, namely, a serpent. The crocodiles of the 

 London clay most nearly resemble a species from the 

 island of Borneo, but "are certainly distinct. The 

 tortoises are some of them freshwater, and there are 



