CRETACEOUS REPTILES. 399 
The neurapophysis terminates below in a very open angle. The vertebra 
appears to have been subject to pressure, and is slightly distorted; but it is 
difficult to conceive how this could have operated partially as to have produced 
the compressed character of the middle of the centrum and have left the two 
articular ends of their natural form. 
In. Lines. 
Antero-posterior diameter of centrum . . . ....2 4 
Transverse diameter of articular surface of ditto. yi) 
Vertical diameter of ditto . Re ce eee 1 7 
Distance between the neurapophysial and costal pits Ee 0 
Transverse diameter of middle of centrum above the 
COStAMPILGMNE Era a <re* o) 6 ie ak Ses Ts” aes anced PLE 
TreerH oF PLEesiosauRi. 
Plesiosaurus Bernardi. 
Two teeth with enameled crowns 1} inch in length when perfect, and half 
an inch in diameter at their circular base, slightly curved and gradually tapering 
to a point, with a few longitudinal enamel ridges of different lengths, and none 
extending to the apex, belong by these characters to the genus Plesiosaurus, 
and are referable by their size to the Pl. Bernardi. The fang or root is 
cylindrical, smooth, and devoid of enamel. One of these teeth, which is figured 
in ‘lab. XXXVII. fig. 8, was obtained from the Scaddlescombe chalk-pit, near 
Lewes, Sussex. The other specimen, ‘lab. XXXVII. fig. 9, is from Southeram, 
Sussex. 
Plesiosaurus constrictus. 
A smaller tooth of a Plesiosaurus with more numerous longitudinal ridges 
(Tab. XXXVII. fig. 13), may probably have belonged to the Plesiosaurus con- 
strictus. This tooth is also from Southeram. 
Plesiosaurus (2). 
A much-fractured tooth (Tab. XXXVII. fig. 15), as thick as those of figs. 9 
& 18, but diminishing more rapidly to the apex, shows similar unequal but more 
numerous ridges all round the enameled surface ; its crown is composed of 
the same kind of hard dentine as in the Crocodiles and Plesiosaurs, with a 
moderately thick covering of enamel. 
3 F2 
