ICHTHYOSATJRID^. 95 



alveolar border of dentary. Teeth (fig. 34) with laterally-com- 

 pressed, carinated and smooth crowns, and their roots invested with 

 cement. Vertebral centra of considerable length, distinctly cupped, 

 and with very prominent costal tubercles. Pelvic limb nearly as 

 large as pectoral ; humerus and femur short and thick ; radiale and 

 adjacent carpale notched ; component bones of paddle of moderate size. 

 Scapula with proximal border long and comparatively straight, with 

 prominent ridge on the anterior border of its dorsal surface. 



This species attains larger dimensions than any other Liassic 

 representative of the'; genus. Assuming that the order is derived 

 from Eeptiles in which the pelvic limb was at least as large as the 

 pectoral, this species may be regarded as the most generalized repre- 

 sentative of the genus. Generalized characters are, moreover, not 

 improbably indicated by the teeth, which resemble those of the 

 Parasuchian Crocodiles and of many Squamata. This species appears 

 to be confined to the Lower Lias. 



Hah. Europe (England). 



2003 *. Slab showing the dorsal aspect of the nearly entire skeleton ; 



(Fig.) from the Lower Lias of Lyme-Regis, Dorsetshire. Although 

 the skull is much smaller than several of the following 

 specimens, the length of this skeleton indicates an indi- 

 vidual of about twenty-four feet in length. The extremity 

 of the caudal region, the right pectoral limb, and the 

 neural spines and chevrons of many of the caudal vertebrae 

 are missing, and have been restored in plaster. The upper 

 surface of the cranium is crushed in, but the contour of the 

 supratemporal fossa is still shown ; and many of the teeth 

 still retain their characteristic crowns. The pelvic limb 

 shows four longitudinal rows of phalangeals, but in the 

 pectoral there are only three such rows remaining. This 

 specimen was obtained by Miss Anning in 1832 ; it is 

 described by Owen in the ' Rep. Brit. Assoc' for 1839, 

 pp. 112-114; and is figured by Hawkins in his 'Sea 

 Dragons,' pi. iii., by Buckland in his ' Geology and Miner- 

 alogy ' (Rridgcwater Treatise), pi. vii., by Kiprijanoff in 

 the ' Mem. Ac. Imp. St. Petcrsbourg,' vol. xxviii. art. 8, 

 pi. xviii., and also by Owen in his ' Liassic Reptilia ' (Mon. 

 Pal. Soc), pt. iii. pi. xxxi. figs. 1 and 3. It is noticed by 

 Mantell in his ' Petrifactions', pp. 381-383. 



Hawlcins Collection. Purchased, 1834. 



R. 808. The middle portion of the skull of a considerably larger 

 individual ; from Lyme-Regis. The left side, from behind 



