REPTILES. 



271 



absorbfcl and finally thrown off. It was supposed by one 

 writer that the Crocodile had so many teeth as there are 

 days in the year. Professor Owen* remarks that the number 

 of teeth developed by a Crocodile, throughout its entire life, 

 would doubtless exceed even this liberal allowance. But with 

 regard to those vvhich are in use at any given time, the 

 number is now well ascertained : the Crocodile of the Nile has 

 sixty-eight; the common Alligator (A. lucius), seventy-six; 

 and the great Gavial {Gavialus Ganjeticus), one hundred and 

 eighteen. 



This notice of saurian reptiles, however slight, cannot be 

 closed without some reference to the strange forms and trigrantic 

 proportions of the fossil species discovered in these countries. 



Fig. 230.— ICHTHVOSADKUS. 



One of them, the Ichthyosaurus {Fig. 230), or Fish-lizard, 

 received that name from some resemblance of the vertebras to 

 those of fishes. Seven or eight species are now known, ex- 

 hibiting singular combinations of structure, such as are no 

 longer found united in any living animal. Some of these 

 individuals were not less than thirty feet in length. They 

 were marine reptiles, preying upon fishes, whose scales and 

 bones, found in hardened masses in the interior of the skele- 

 tons, and strewed elsewhere in great abundance, unfold a tale 

 respecting the former inhabitants of the ancient ocean from 

 which these islands were ujiheaved. 



Fig. 231.— Plesiosacru.s. 



Another genus is that of the Plesiosaurusf {Fig. 281). 

 To the head of a Lizard is united the teeth of a Crocodile ; 



» Odontogrr.phy, p. 286. 



f From two Greek words, meaning "near to" and a '-Lizard." 



