PROF. H. G. SEELEY OST ARISTOSTTCHUS PUSILLUS. 



227 



the first process. Its upper aspect is angular, with an oblique ridge 

 extending outward and forward to its superior angle. 



The transverse process of the third vertebra is on a level with the 

 neural canal and has a strong base. It is 12 or 13 millimetres long, 

 is in the middle of the length of the vertebra, and forms a vertically 

 compressed lamina (fig. 14, 3). It is slightly convex below and flat- 

 tened above, with a sharp ridge on its anterior margin, which extends 

 obliquely inward and backward, and ascends the side of the meta- 

 pophysis, inclined obliquely backward. 



In the fourth vertebra the transverse process is much stronger. 

 It arises from the anterior half of the centrum, and like the process 

 from the preceding vertebra is partly on the centrum and partly on 

 the neural arch. It is elongated in the antero-posterior direction, 

 subreniform on the articular facet, which is expanded, and flattened 

 and convex below, 17 millimetres long, about 8 millimetres deep 

 behind, and less in front (fig. 14, 4). A strong transverse ridge on 

 the hinder part of the upper surface defines an anterior concave area, 

 and ascends the middle of the metapophysis. The transverse mea- 

 surement between the facets for the ilia, as in the previous vertebra, 

 is about 3 centimetres. 



The process on the fifth vertebra is of about the same length. Its 

 antero-posterior extent, 17 millimetres, is slightly greater, but it is less 

 deep. It is flattened on the underside. The outline of the facet 

 for the ilium is subtriangular, owing to the very strong development 

 of the ridge on its upper surface. This ridge extends obliquely 

 forward so as to define an anterior concave cup-like depression, and 

 a posterior oblique arda on which is a tubercle which represents the 

 metapophysis. On this vertebra the facets of the postzygapophyses 

 are developed (fig. 14jpz). The transverse measurement over them 

 is 12 millimetres ; tlzey are divided posteriorly by a deep vertical 

 furrow which ascends the neural spine so far as it is preserved. 

 They have the usual ovate form, and look obliquely downward and 

 outward. Only the margin of the posterior surface of the centrum 

 is exposed. 



The outlets for the sacral nerves are through round foramina, 

 situate between the centrum and the neural arch, at the junction of 

 two vertebras (fig. 14, / ). They are seen on the left side in the 

 second vertebra, and on the right side in the third and fifth. 



The half of the dorsal vertebra preserved has the centrum 2 centi- 

 metres long at the base and 2*2 centimetres long on the neural canal, 

 and this indicates that the back was arched. The articular ends of 

 the centrum are very slightly concave, with a ligamentous marking 

 at the external border. The middle of the centrum is constricted 

 and rounded at the base. The transverse process is thin and given 

 off above the neural canal. From the neural platform an anterior 

 ridge descends almost vertically, and another ridge descends obliquely 

 behind it. The height of the platform from the base of the centrum 

 is 2*3 centimetres.- The height of the centrum is 1-4 centimetre. 



Only a fragment of a caudal vertebra is preserved. It is similar 

 in form to that figured by Sir H. Owen, and similar to that attri- 



