.S2 J. W. HULKE ON THE VERTEBE-S: OE OENITHOPSIS. 



(diapophysis) springs from the arcli vertically over the lower, towards 

 which it inclines ; and both processes are joined by the branches of 

 a short forked riblet, which assist to enclose a large foramen. The 

 only riblet preserved is mutilated ; but it is evident that its unat- 

 tached, free, distal border was extended forwards and backwards in 

 a direction nearly parallel with the vertebral column in an ordinary 

 manner. Erom the root of the diapophysis another projecting ledge- 

 like plate descends along the side of the arch towards the junction 

 of this with the centrum near the posterior border of this latter, 

 thus taking a direction approximately parallel with the lower plate. 

 Between these two plates, and much overhung by the upper one, 

 the side of the centrum is impressed with a long narrow pit, crossed 

 slantingly and imperfectly subdivided by ridges. From each of 

 the neural crests, where these diverge behind, a prominent ridge 

 runs downwards and forwards towards the root of the diapophysis 

 of the same side, and another wider ridge descends nearly vertically 

 towards the centrum, its posterior margin forming the lateral boun- 

 dary of the posterior opening of the neural canal. Between these 

 two ridges, and above the diapophysial ledge-plate which bounds it 

 below, is a large very conspicuous depression. The average length 

 of the three cervical centra was probably not under 28 centim., 

 which is about the length of the centrum I brought before the 

 Society last June. The large extent of the articular surfaces, the 

 crests and ridges, and the great length of the vertebrae indicate a 

 very long, extremely mobile, strongly muscular neck. In the sin- 

 gular flatness of the under surface of the centrum there is a striking 

 resemblance to that of Apteryoc Mantelli. 



Trunk- Vertehrce. — The best-preserved vertebra in Mr. Fox's col- 

 lection (PL III. figs. 4, 5) referable to the trunk is, I beheve, from 

 nearly the same situation as the neural arch I brought under the 

 Society's notice in 1870. When placed on a plane surface, its height, 

 taken from this to the top of its spinous process, is about 62 centim. 

 The centrum is opisthocoelous ; but the prominence of the articular 

 ball is less than in the neck. The horizontal diameter of the ball is 

 greater than the vertical diameter, the actual measurements being 

 22'5 centim. and 14*6 centim. The length of the centrum taken 

 along the side from the base of the ball to the edge of the cup is, in 

 the present state of the fossil, 17*5 centim. ; but before abrasion 

 it was probably not less than 20 centim. The under surface of 

 the centrum is flattened transversely, but to a much smaller degree 

 than in the neck. Longitudinally it is rendered very concave by the 

 swelling of the articular ends. It is marked by a low median ridge. 

 In the side of the centrum is the conspicuous opening of the large 

 internal chamber, described more particularly in my last note. It 

 is of an oval form, with the larger end in front. Its length is 13*5 

 centim., and its greatest vertical diameter is 5*4 centim. The 

 chambers of opposite sides are separated only by a very thin median 

 partition. The neurapophyses have an extensive attachment to the 

 centrum, their antero-posterior extent nearly equalliflg that of the 

 latter. They then contract to 13 centim. at a height of 1*5 centim. 



