Type of the Genus Massospondylus, 107 



vertical truncation of tlie anterior parts of the sides, so as to 

 leave only a narrow vertical median strip of the centrum to 

 meet the sacral vertebrae, which was placed in front. Tliis is 

 due to the encroachment of tiie sacral ribs, which were situate, 

 at the junction of the two vertebra?, as in most of the Old- World 

 Saurischia and as in Deuterosaurua. 'Wa encroachment of 

 the sacral ribs, no less than the short len^^th of the centrum, 

 indicates that the sacrum was consolidated early in life. Tlie 

 centrum is less than 2 inches long, lf\, inch deep, ly^^ inch 

 wide. 



Caudal VertehrfB. (Fig. 3.) 



The vertebrae which have been regarded as caudal all retain 

 the transverse processes above the level of the base of the 

 neural canal. The centrum (fig. 3) has a conspicuous lateral 

 compression in the middle, rounded base, and large facets for 

 the chevron-bones. The articular surface is conically concave 



Fig. 3. 



- Chevron surf 



{Right side of centrum, early caudal vertebra. ^ nat. size. 

 No. SSS reversed. 



in front and more flattened behind, with a rather small neural 

 canal and depressed neural arch, with the neural spine inclined 

 backward. The sj)ine diminishes in height as the vertebrse 

 diminish in size. The caudal vertebr£e are referable to more 

 than one individual. 



Pelvis. 



Sir R. Owen identified the ilium 358 and the ischium 359. 

 He remarks that the left ilium terminates anteriorly in a 

 short obtuse process in advance of the acetabulum ; but it is 

 supposed that its anterior part has been broken away, and the 

 bone in form and proportions was said (1854) to most resemble 

 the iliac bone of Ljuanodon. Notwithstanding some uncer- 

 tainty in determination of tlieiliun) in allied animals in iSir It. 

 Owen's later writings, these remarks appear to indicate that the 

 pelvic aflinities of the animal were rightly appreciated. 



