KIMMERIDGIAN DINOSAURS. 



563 



and thrust a little mesiad and forward. This bone will be subsequently described 

 showing the proportion of the acetabular cavity contributed by it. 



Anterior to the pelvis is a dislocated group of eight hinder trunk-vertebrae, each 

 retaining more or less of its neural arch and processes. On the right side of the pelvis a 

 complete dorsal vertebra is exposed, measuring 1 foot 5 inches in length and 13 inches 

 in breadth, between the diapophyses. The centrum is 3 inches 9 lines in length, 

 5 inches in breadth, 4^ inches in height, to the base of the neural canal ; the hinder 

 outlet of this is pyriform, the apex about 2^ inches in vertical, and 1^ incehe in 

 transverse, diameters. Trom the floor of the neural canal to the base of the spine is 

 8 inches ; the length of the spine is 5 inches. 



Beyond this dorsal vertebra is the body of a caudal one, showing a greater degree of 

 concavity of the fore surface of the centrum, which has a breadth of G inches. 



Behind the sacrum is a dislocated group of four caudal vertebrae, mainly agreeing 

 in character with the subject of Pis. 67 and 68. 



Caudal Vertebrae. — The vertebra of Omosaurus which has been most perfectly 

 wrought out of the matrix is one from the base of the tail ; it was in the same block 

 with the sacrum, not far from the hind part of the pelvis. 



This anterior caudal vertebra forms the subject of ' Dinosauria,' Pis. 67 and 68, of the 

 natural size ; and I here subjoin, also, the following admeasurements : 



Height or vertical extent of the entire vertebr 



Breadth of ditto 



Length at the zygapophyses, giving extreme 

 Centrum, length, lower surface 

 „ „ upper surface 



„ breadth, anterior surface 



„ ,, posterior surface 



„ height, anterior surface 



„ ,, posterior surface 



Neural canal, vertical diameter 



„ transverse diameter, least 



Neural arch, breadth at upper level of centra 

 „ „ across prezygapophyses 



„ postzygapophyses 

 Pleurapophysis, length from base to apex 



„ depth from tubercle to under 



„ thickness, extreme, at base 



„ „ at tubercle 



„ „ below tubercle 



length of neural arch 



n 



surface 



