BRITISH FOSSIL REPTILES. 117 



gularly fluted ; a smooth boundary divides it from the crown, 

 which is trarersed by liner grooves converging to the apex ; the 

 transverse section of the crown is nearly circular, not com- 

 pressed as in Ich. j)latyodo)i ; it tapers gradually to the apex, 

 which is nearer the posterior line than the central axis of the 

 tooth. 



The vertebrae are thicker in their antero-posterior diameter 

 than in the Icli. platyodon : I count 45 between the occiput 

 and pelvis, and 120 in the skeleton above-cited; but the tail is 

 slightly imperfect. The scapula of the Ich. lonchiodon is more 

 equably and deeply concave at the posterior margin, and its 

 humeral extremity is relatively broader than in the Ich. platyo- 

 don. The bones of the extremities are thicker but shorter : the 

 radius is emarginate anteriorly : there are three phalanges, of 

 which the ossicles resemble in form those of the Ich. platyodon : 

 but the whole paddle is relatively less. This difference is still 

 more marked in the hind-paddle, which in the Ich. platyodo?i 

 is, on the contrary, very nearly equal in size with the fore-paddle. 

 Locality. — The lias of Lyme Regis, where the skeleton above^ 

 noticed was discovered by Miss Anning. 



Ichthyosaurus tenuirostris*, Conybeare. 



grandipes, Sharpe. 



chirostrongulostinus, Hawkins. 



The form of tooth figured by Mr. Conybeare as characteristic 

 of the Ich. tenuirostris is one which it is very difficult to di- 

 stinguish from that which is presented by the teeth of a species 

 next to be described, and which in the form of its head is in- 

 termediate to the species called Ich. intermedius and/cA. tenui~ 

 rostris. This species may, however, be recognised by other 

 characters afforded by the humerus, the radius and tibia, and 

 by the size and form of the paddle-bones, which have suggested 

 the synonyms to their respective authors cited at the head of 

 the present chapter. 



But the most striking peculiarity of the Ichthyosaurus tenui- 

 rostris is that which Mr. Conybeare has happily chosen for its 

 specific denomination, viz. the great length and slenderness of 

 the jaw-bones, which are analogous in this respect to those of 

 the Gharrial, and which, in combination with the large orbits 

 and flattened cranium, give to its entire skull a close resemblance 

 to that of a gigantic Scolopax, with a bill armed with teeth. 

 The length of the snout is chiefly due to the prolongation of 



* The characters derived from the relative length of the head, trunk, and 

 tail, and of the fore and hind paddle, quoted from Cuvicr, and assigned to 

 the present species by H. V. Meyer, in his work entitled " Pal^o/offica," 

 p. 214, are tiiose of the Ich. intermedius, to which species the small specimen 

 figured by Home, in the Philosophical Transactions for 1819, and now in the 

 Museum of the Royal College of Surgeons in London, belongs, and not, as 

 Cuvier supposed, to the Ich. tenuirostris. 



