360 THE PORTLAND OOLITE PERIOD. CHAP. 



Length, 1*80 inch; breadth, 2'45 ; height to canal, 2*25; to 

 margin of canal, 2*45. 



The vertebrse placed farther back about the middle have distinct 

 surfaces for the hsemapophyses, and separate bases for the di- 

 apophyses, much resembling those of P. brachydeirus. 



Diagram CLV. Caudal vertebra of Pleiosaurus gamma. Scale one-fifth of nature. 

 I. Seen sideways. i. Seen from below. 



Length, 175 inch; breadth, 2-60; height, 2*40 (2*50). 

 The articulating surfaces are nearly plane, and deeply pitted in 

 the middle. 



PLEIOSAURUS NITIDUS. n.s. 



A few vertebrse of a fourth species, of smaller size than those 

 already mentioned, occur in the Kimmeridge clay of Shotover 

 cervical, dorsal, and caudal remarkable for neatness and com- 

 parative smoothness of surface. 



The cervical vertebra has oval faces of articulation, remarkably 



Diagram CLV I. Cervical of Pleiosaurus laevis or nitidus. Scale one-fifth of nature, 

 i. Seen from above. 2. Seen in front. 3. Seen sideways. 



rounded and somewhat plaited at the edges, flat over most of the 

 surface, but depressed and somewhat puckered in the middle. 

 The neural canal is unusually wide, flat, and expanding retrally, 

 with two foramina. The diapophysial cicatrix is long, not deep, 

 but marked across so as to indicate division in a more forward- 

 placed vertebra. 



Length, i'2 inch; breadth, 2*6; height, 2-15 (2*20). 



The dorsal vertebra has several points of peculiarity. [Regarded 



