§ 31. REPTILES OF THE JURASSIC SYSTEM. 531 



extinct reptiles have been found more or less abundantly 

 in every deposit. Upwards of fifty species, belonging to 

 several genera, have been determined by the various natural- 

 ists who have treated on this subject. Those of the British 

 strata have been accurately investigated and described by 

 Professor Owen, whose memoir, in the Reports of the 

 British Association for 1840 and 1841, presents a masterly 

 and comprehensive view of the fossil reptiles at that time 

 known. As I shall have occasion to recur to this subject 

 in the sequel, it will be sufficient in this place briefly to 

 enumerate the principal kinds hitherto discovered in the 

 Oolite and Lias. 



In addition to the reptiles of which remains have been 

 found in the Chalk and Wealden, namely the Megalosau- 

 rus {ante, p. 421), Poecilopleuron (p. 417), Cetiosaurus 

 (p. 412), Strep tospondylus, Pterodactylus, Ichthyosaurus, 

 Plesiosaurus, — and of some of these, especially of the 

 two last-named genera, numerous species abound in the 

 Lias, and Oolite, — several other Crocodilian and Lacer- 

 tian reptiles, with peculiar osteological modifications, also 

 occur. These are the Teleosaurus, Steneosaurus, &c* 

 which are characterized by their long narrow muzzles, 

 sharp-pointed teeth, short forelegs, imbricated scales, and 

 doubly concave or flat vertebras : their relics are chiefly 

 found in the middle and lower Oolite. 



The most remarkable circumstance relating to the Ich- 

 thyosauri and Plesiosauri that swarm in the Lias, is the 

 connected state in which all the bones of the skeleton occur. 

 The entire osseous frame-work, from the extremity of 

 the snout to the last vertebra of the tail, often remains 

 entire, or but very little displaced from its natural posi- 

 tion ; even the bones of the paddles, with their cartilagi- 

 nous appendages, are in some instances preserved, f The 

 indigestible portion of the food of these carnivorous marine 



* See Medals of Creation, vol. ii. p. 723. f Ibid. p. 713. 



VOL. II. N N 



