66 PLESIOSA.URUS. 



3. Ichthyosaurus tenuirostris, Phil. Trans. 1819, t. 15. 

 Cuv. Os. Fos. V. t. 28, f. 1 , t. 29, f. 8, 9, t. 28, f. 6, 7, 8. 



Muzzle long and slender ; teeth slender. 



4. Ichthyosaurus intermedius, Cuv. Os. Fos. v. t. 29, 

 f. 2, 5. 



Teeth more acute and less deeply striated than in /. com- 

 munis, but less slender than in I, tenuirostris. 



6. Ichthyosaurus grandipes, Sharp, Proceed. Geol. Soc. 

 xvi. 222. 



The vertebra three-fifths the length of its breath ; the pad- 

 dle large ; humerus one-fifth the length of the animal ; the 

 ulna or radius notched on the outer edge ; phalanges circular 

 or oval. Teeth — — ? In the Ichth. communis, tenuirostris, 

 and intermedius, the phalanges are angular. 



6. Ichthyosaurus latifrons, [Broad-headed Ichthyosaurus.) 

 Koenig, Icon. Fos. Sect. ii. t. ined. (v. Mus. Brit.) 

 Fos. Northamptonshire. 



See also Ichthyosaurus uniformis, Fleming, Brit. Anim. 154. 



Gen. III. PLESIOSAURUS. Conybeare. 



Caput parvum ; coUum longum, vertebris numerosis ; 

 dentes in foveolis inserti. 



The head is small, about one-fifth the length of the neck, 

 with the teeth inserted in small pits. The neck is very long, 

 with about 25 vertebrae ; the body about 4 times, and the 

 tail 5 times, the length of the head. The vertebrae resemble 

 those of the Crocodiles. The paddles are longer than those of 

 the Ichthyosauri, but they may vary in the species. 



1. Plesiosaurusdolichodeirus, [Long-necked Plesiosaurus.) 

 Cuv. Os. Fos. v. t. 31. Geol. Trans, series i. t. 48, 



Fos. Lyme Regis in Com. Dorset. 



/3. Homii, Home. Phil. Trans. 1818, t. 



2. Plesiosaurus carinatns. Vertebris carinatis. Cuv. Os. 

 Fos. V. 486. 



Fossil in the Oolite of Boulogne. 



