LIFE AND KINSHIP OF DINOSAURS. 599 



surfaces of the centrum in such dorsal vertebrae as are figured in ' Dinosauria' Pis. 65 

 and 6G of the present Work, and in corresponding vertebree of lyuanodon, Megahsaurus, 

 Cetiosaurits, Hylaosaurus, Scelidosaurus, BothriosjoondyJus, figured in previous plates. 

 Not that the flatness of both ends of the centrum is absolute, but the deviation is 

 slight and usually, when in the direction of concavity, confined to the hinder surface (as 

 in the Dinosaurian vertebra, fig. 5, PL 4, above cited). Neither must it be supposed 

 that the dorsal series may be ' aniphiccclous ' in one Dinosaur, or ' opisthocoelous ' in 

 another. 



The centrum in some Dinosaurs, Tapinocephalm, e. g., shows at the middle of its flat 

 articular surface a foramen one sixth the diameter of such surface. It is the base of a 

 small conical cavity, the apex of which meets that of the cone of the opposite side, — a 

 beaded remnant of the notochord appearing to have traversed the vertebral column. In 

 other species examined by me certain cervical vertebrae and a few consecutive dorsal 

 vertebrte are 'opisthoccelian,' /. e. have the 'ball' in front (fig. 4, PI. 4, above cited); 

 and the convexity, in certain of these, does not wholly subside until the lumbar region is 

 reached. But whence did Professor Huxley derive his knowledge of the ' opistho- 

 coelous' character in ' pacliypodal Saurians' ? If from the original definition of the 

 Dinosaurian group,* that character, as there limited, seems to have stood the test of 



time. 



The discoverers of the Jguanodon and Megahsaurus believed the ball to be behind, 



and von Meyer accepted this view of the conformity of the Dinosaurian with the Croco- 

 dilian dorsal centrums. In fact, the way to distinguish the fore from the hind end of a 

 fossil saurian vertebra seems not to have been known to their describers until the test was 

 defined in 1S41. This knowledge, howsoever acquired by the writer of the "Cha- 

 racter 1," here discussed, is applied by him in error to Dinosauria : in them the ball 

 subsides at the beginning of the dorsal series.f I would further remark, that, as there are 

 many modifications and characteristics of the so-called ' capitular transverse processes' and 

 ' tubercular transverse processes,' in the varied series, including Dinosaurian, of vertebral 

 structures, the advantage of single substantive terms is exemplified by the convenience 

 and helpfulness to precise description which such terms aff'ord, adjectively, in predicating 

 of ' parapophysial ' and ' diapophysial ' modifications. 



And if by ' capitular portion of the transverse process' Professor Huxley may mean 

 ' parapophysis,' and by ' tubercular portion of the transverse process ' ' diapophysis,' J I 

 have then to object that the ' dorsal vertebrae ' of Omosaurus do not all possess the two 

 kinds of processes. In the subjects of Pis. G6 and C7 the head of the rib is received 

 by a pit, not articulated to a ' capitular process.' The dorsal vertebrae, of which the ribs 



* ' Report on Brit. Foss. Reptile?,' p. 91 : " Remarks on Mantell's ' Fourth System' of Vertebrae from 

 the Wealden." 

 t lb., ib. 

 X ' Quarterly Journal of the Geological Society,' vol. xx.xi, p. 426.' 



13 b 



