214 Prof. R. Owen on the Occurrence 



with that of Chondrosteosaurus. In Iguanodon the breadth of 

 the humeral end is two sevenths the length of the scapula ; in 

 Cetiosaurus it is not quite one half that length ; in Scelido- 

 saurus it is one half that length 5 in Chondrosteosaurus it is two 

 thirds that length. In the degree of expansion of the humeral 

 end of the scapula the Scelidosaurus^ amongst the Dinosauria 

 as known to me, makes the nearest approach to Chondrosteo- 

 saurus. The part called " mesoscapular process " is not 

 indicated in Prof. Cope's figure. On the supposition that it 

 may be the low ridge there shown, a similar ridge from the 

 middle of the anterior border of the bone is indicated in the 

 scapula of Scelidosaurus. 



The coarse pitting of the articular surfaces of the limb- 

 bones and arches are most common and best marked in the 

 marine Reptilia [Ichthyo- and Sauro-pterygia) ; the degree in 

 which the same character is marked and prevails in the limb- 

 bones of other Saurians points to the predominance of the sea 

 over the land as the theatres of their life-acting. This infer- 

 ence I have drawn and applied to the Cetiosauri ; it is as 

 legitimate an application in considerations of the way and 

 medium of life of Chondrosteosaurus. Not that I deem the 

 Cetiosaurs or any form of Dinosauria to be as exclusively 

 aquatic as the Plesiosaurs ; but the degree or proportion of 

 their time passed in water may be inferred from such a 

 character as that noted by Prof. Cope in the articular surfaces 

 of the scapula and in those of the acquired long bones and 

 limb-bones of Chondrosteosaur^is. 



On the pneumatic hypothesis of the cancellous structure of 

 the vertebrge, the conclusion drawn by Prof. Seeley would be 

 equally just and legitimate, viz. that such huge Dinosaurs 

 were " constructed after the lightest and airiest plan, such as 

 is only seen in Pterodactyles and in birds," that the species 

 is " therefore clearly ornithic " and entitled to the designa- 

 tion of Ormthopsis^. 



Prof. Cope, indeed, accepts the consequent inference, viz. that 

 Chondrosteosaurus " carried its neck erect after the manner of 

 birds ;" but he prefers to compare the reptile, on the assumed 

 concomitant length of ahypotlietical humerus, to the giraffe. 



As, however, I find the closest resemblance of the parts of 

 the framework of Chondrosteosaurus, of which such acceptable 

 additions have been brought to our cognizance through the 

 praiseworthy labours of Prof. Cope and Mr. Lucasf, to those of 

 previously known Dinosauria, it is in that order that I find 



* Ann. & Mag. Nat. Hist. 1870, 4tli ser. vol. v. p. 279. 

 t To the latter gentleman the Professor bears the following testimony : 

 — " Credit is due to Superintendent O. W. Lucas for this discovery, and 



