370 



THE PORTLAND OOLITE PERIOD. 



CHAP. 



In No. 6. Length, 2*5 inches ; breadth, 4/00 ; height to canal, 



3' 1 - 



In No. 12. Length, 2*55 inches ; breadth, 3-82 ; height to canal, 



3'35- 



The articulating faces are nearly circular. 



The three vertebra from Marcham, posterior dorsals, have the 

 zygapophyses widened and reduced in prominence. With the same 

 breadth, they are deeper and longer than the Shotover examples. 

 Length, 3*03 inches; breadth, 4/20 ; height to canal, 4*10, 



Diagram CLXX. Dorsal vertebra of Plesiosaurus brachyspondylus. 

 Seen on the left side. 



In proportion to the dorsal vertebrae of some other species, these 

 may be regarded as short; and it has been usual in the Oxford 

 collection to mark them by the name Plesiosaurus brachyspondylus, 

 given by Professor Owen d . 



PLESIOSAURUS VALIDUS. n.s. 



Of this large and fine species the clay pits of Shotover, Cumnor, 

 and Baldon have furnished many examples. They include two sets 

 of cervicals, a few dorsals and lumbars, and a considerable series 

 of caudals. The cervicals begin small and increase regularly through 

 a series of twenty-six, without in that length undergoing much 

 change of form, except that in the last the lateral cicatrix has 

 ascended considerably toward the dorsal region, and is almost con- 

 nected with the base of the neurapophysis. 



d Keport on Fossil Reptiles, 1839. 



