482 SAURIANS. 



manner as the Ornithorhyncus, of Australia, which seeks its food 

 at the bottom of lakes and rivers, and is obliged, like the Ichthy- 

 osaurus, to be continually rising to the surface to breathe air." 

 To this sternal arch the front paddles are articulated; they are 

 nearly one-half larger than the posterior paddles, and in this part 

 of the structure the cetaceous type appears to have been flattened. 

 The bones of the head, the length of the muzzle, and the teeth, 

 sometimes amounting to one hundred and eighty in number, pre- 

 sent analogies to those of the Crocodile. The eyes, however, 

 were extremely large, much larger than those of the latter ani- 

 mal, and we can easily imagine, glared ferociously as the mon- 

 ster darted towards its prey. Six different species have been 

 enumerated. The commonest species, 7. tenuirostres, (Lat. thin- 

 beaked,) reaches the length of fourteen feet. The species /. 

 platyodon, (Gr. plains, broad or large, and odous, tooth,) has 

 been seen in specimens thirty feet long. The teeth are some- 

 times two and a half inches in length ; and the orbit (of the eye) 

 one foot in diameter. The vertebrae are one hundred and twenty 

 in number. There is no evidence whatever that one species has 

 succeeded, or been the result of the transmutation of a former 

 species. 



It should be added, that the first remains of the Ichthyosaurus 

 were collected by a lady, Miss Anning, from the cliffs of 

 Lyme Regis, Eng. The Ichthyosaurians are abundant through- 

 out the Lias and Oolitic formations. 



Phsiosaurus, (Gr. plesios, next; sauros, a lizard.) This 

 genus was first described by Conybeare, in 1821. Its most 

 remarkable character pertains to the vertebrae of the neck, 

 which are from twenty to forty in number, (see Chart;) more 

 than in any other known animal. Conybeare conjectures, that 

 as this creature 4^'eathed air, and had frequent need of respira- 

 tion, it usually swam upon or near the surface of the water, 

 arching back its long neck like the Swan, and plunging down- 

 wards at the fishes coming within its reach. Cuvier asserts, 

 " To the head of a Lizard, the Plesiosaurus united the tail of 

 a Crocodile ; a neck of enormous length, resembling the body of 

 a Serpent ; a trunk and tail having the proportions of an ordinary 

 quadruped ; the ribs of a Chameleon, and the paddies of a 

 Whale." The greater length of its extremities would seem to 

 indicate that movement on land was probably less difficult for 

 this creature than for the Ichthyosaurus. It was, probably, in 

 general, about ten feet long; though some species of this genus 

 and the preceding one, must have exceeded twenty feet in length. 



