﻿FOSSIL REPTILIA OF THE 



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-vertebras, 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 1J inches in 

 transverse, diameters. From 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 6 inches. 



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

 in character with the subject of Pis. XIV and XV. 



§ 6. 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 Pis. XIV and XV, of the natural 

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



In. Lines. 



Height or vertical extent of the entire vertebra 



14 



9 



Breadth of ditto ..... 



14 



6 



Length at the zygapophyses, giving extreme length of neural arch . 



4 



2 



Centrum, length, lower surface .... 



2 



10 



„ „ upper surface .... 



2 



5 



„ breadth, anterior surface 



5 



8 



„ „ posterior surface 



6 







„ height, anterior surface 



4 



5 



„ ,, posterior surface 



4 



6 



Neural canal, vertical diameter . 



2 







„ transverse diameter, least 



1 



4 



Neural arch, breadth at upper level of centrum 



5 



8 



„ „ across prezygapophyses 



4 



5 



„ postzygapophyses 



2 



2 



Pleurapophysis, length from base to apex 



4 







,, depth from tubercle to under surface . 



2 



3 



„ thickness, extreme, at base . 



1 



6 



„ at tubercle 







10 



„ ,, below tubercle 







8 



