FEOM THE KIMMERIDGE CLAY. 441 



The atlas and axis are lost. In No. 1 of the cervical series the 

 lower transverse process or parapophysis, preserved only on the left 

 side, is an oval facet 5x4 millims. in extent, which projects from 

 the side of the centrum, near its anterior border, below the semi- 

 diameter. Close behind it, agglutinated to the centrum by matrix, 

 is a small hatchet-shaped bone, having on one margin an articular 

 facet, the form and size of which so nearly agree with those of the 

 parapophysis as to suggest, in connexion with its nearness to this, 

 that it is a neck-riblet. The sides of this centrum are convex in 

 the vertical directiou. From the size and position of the parapo- 

 physis, I think it probable that this vertebra was next to the 

 axis, or the third in natural sequence. 



In jS"o. 2 the parapophysis is higher on the side of the centrum ; 

 it is also more prominent than in 'No. 1. It is close to the anterior 

 border of the centrum, just external to the neuro-central suture. 

 From it there passes backwards a ridge which divides the side of 

 the centrum into a smaller upper area lying between the ridge and 

 neuro-central suture and a larger lower area between the ridge and 

 inferior median keel. The depression (mentioned in the description 

 of No. 1) is in the lower area ; and its deepest'part is in front. A 

 large vascular foramen pierces the bottom of the depression. The 

 middle of the centrum is constricted, the horizontal transverse dia- 

 meter being here 29 millims., whilst at the ends it is 40 millims. 

 The upper surface of the centrum contributes at each end a large 

 triangular piece to the floor of the neural canal ; but at the middle 

 of the canal only a narrow piece of it appears between the neura- 

 pophyses. 



In jSTo. 3 the parapophysis touches the neuro-central suture, 

 which in front spreads outwards on its upper surface. The neura- 

 pophysis in this, as in all the neck-vertebree, has an extensive attach- 

 ment to the centrum, its antero-posterior dimension nearly equalling 

 that of the upper surface of the centrum. At each end it spreads 

 out very conspicuously. The arch, of which more is preserved than 

 in any other neck- vertebra, was evidently dwarfed. On its left side, 

 just external to the praezygapophysis, are indications of an upper 

 transverse process for attachment of rib-tubercle, now broken oif, a 

 diapophysis, in the level of the spring of the arch. 



In No. 4 the parapophysial facet rests jointly on the centrum 

 and neurapophysis ; but the former constitutes the greater part. 



In No. 5 the parapophysis is similarly situated ; but in No. 6 it 

 is on a slightly higher level, the centrum contributing the lesser 

 part. 



In No. 7 the parapophysial facet lies just above the neuro- 

 central suture, on the dilated antero-external corner of the neura- 

 pophysis. 



In No. 8 no distinct trace of rib-facet is perceptible here ; and 

 in No, 9 the facet has certainly risen above the base of the neura- 

 jjophysis. 



Accounting all cervical in which the supporting process for the 

 attachment of the rib-head is wholly or partly on the centrum, the 



