208 Prof, R. Owen on the Occurrence 



median lateral processes described above. The di apophyses 

 are much larger, and the zygapophyses more extended trans- 

 versely. The centrum is constricted at the middle, and espe- 

 cially just behind the convex articular extremity, whose cir- 

 cumference forms a prominent rim. The edges of the lip are 

 flared outwards, forming a deep basin, much wider than deep. 

 The fossse described in the last vertebra are present in this 

 one, but differ in proportions, owing to the greater size and 

 expanse of the superior parts of the neural arch. The fossa 

 posterior to the base of the diapophysis is nearly plane, while 

 that at the anterior base is deeply excavated, is narrower, and 

 extends so far along the inferior side of the process as to give 

 it a semicircular section near the middle. Distally the dia- 

 pophysis has a trialate section, owing to its three longitudinal 

 ridges ; and the articular extremity is large and antero-poste- 

 rior in direction. The process differs from that of the verte- 

 bra already described, in the possession of a facet near the 

 middle of its anterior inferior bounding ridge, which is pro- 

 bably costal, as in the vertebrae of Crocodilia. The lateral 

 foramen of the centrum is subround. The general surface is 

 smooth " *. 



The neural arch is confluent with the centrum. 

 In a later account of the gigantic Saurian f the dorsal ver- 

 tebras are again stated to be " remarkable for the enormous 

 elevation of the superior arches and diapophyses, the result of 

 which is to give the ribs an unusually elevated basis, and the 

 cavity of the body much space above the vertebral axis on 

 each side. On the other hand the bones of the tail and limbs 

 are solid or nearly so, in great contrast with some of the 

 Dinosauria of later geological periods. Another peculiarity 

 is the probable great length of the anterior limbs. The sca- 

 pula is enormous as compared with the pelvic bones. The 

 sacrum is also small and short, showing that the weight was 

 not borne on the hinder limbs." It appears also that Chondros- 

 teosaurus resembled Cetiosaurus in the " pitted surface of the 

 articular end of the limb-bones." 



Reverting to character 2, common to Chondrosteosaurus 

 and the Dakota monster, it will be seen that there is a differ- 

 ence of opinion between Prof. Cope and myself as to the con- 

 tents, in the living giants, of the " huge internal sinuses " of 

 their vertebral centi-ums. In the Wealden fossils, and, I 

 suppose, also in the Dakota ones, they are occupied by mine- 

 ral matter derived from the matrix. When Prof. Cops, states 



* Pal. Bull. pp. 8, 9. 



t ' Proceedings of the American Philosophical Society,' vol. xvii. 

 no. 100, May to December, 1877, p. 233. 



