388 BRITISH FOSSIL REPTILES. 



relatively larger than in fig. 11. In fig. 1 5 more of the hase of the neural spine 

 remains than in most other specimens. 



Figs. 17 and 18 are of a rather shorter and probably more advanced cervdcal 

 vertebra, but of very similar proportions ; in it the neural arch (fig. 1 7) is more entire 

 than in most specimens, the anterior (a) as well as posterior (z) zygapophyses being 

 preserved ; the more frequent loss of the anterior pair is due to their being more 

 slender and more produced. The under surface of the centrum (fig. 18) shows no 

 rising of the part midway between the two ends, the hypapophysis having a less 

 extended base than in the vertebra, (fig. 12). The inner surface of the anterior 

 zygapophysis (fig. 18, a), is divided by a notch from the border of the articular con- 

 cavity of the centrum. 



Fig. 1 9 gives a view of a section of a mutilated cervical vertebra, nearly equal in 

 size with fig. 7, and similar in form. The shape of the neural canal, the large cancelli, 

 and the thin superficial compact crust of the bone, are well shown in this section. 



At the base of the neck, or beginning of the back, the vertebrae suddenly decrease 

 in length ; the hypapophysis disappears, or is represented only by a shght production 

 of the lower border ol" the anterior cup ; the hind parapophyses are less produced, the 

 lower surface of the centrum is flattened, and presents the quadrate form shown in 

 figure 20. There is now a considerable development from the fore part of each side 

 of the neural arch and contiguous part of the centrum, and thereby the last cervical 

 or first dorsal vertebra of the Pterodactyle more resembles the corresponding 

 vertebra of the bird. A front or proper parapophysis, a diapophysis, and a rudimental 

 rib are present on each side, and coalesce around the vertebraterial foramen ; an 

 oblique ridge is continvied from the upper border of the anterior articular cup upon 

 the parapophysis ; a parallel oblique ridge is continued from the anterior zygapophysis 

 downward and outward upon the pleuraj^ophysis ; the diapophysis makes a low 

 obtuse projection above the pleurapophysis and behind the zygapophysis. Above 

 these developments the neural arch contracts from before backward, to an extent 

 of 5 lines, as compared with a total vertebral breadth, anteriorly, of 1 inch 8 lines ; 

 it then rapidly expands, rising vertically at its fore part, and developing at its back 

 part the posterior zygapophyses, the articular facets of which look more directly 

 outward than in the long cervical vertebrae ; the superincumbent tubercle (PI. 8, 

 fig. 22, c) is more distinct from the facet (ib., z) ; the posterior zygapophyses are also 

 much more approximated than in those vertebrae ; they are separated behind by a 

 semicircular concavity ; the base of the neural spine in the vertebra here described 

 measured G lines in length by 3 in breadth. The pneumatic foramina are at the 

 back part of the base of the diapophysis, as I have seen them in the cervical vertebra 

 of a Dinornis. The articular surfaces of the centrum retain the transversely 

 extended form, and are simply concave before and convex behind, which at once 

 distinguishes the Pterosaurian hind-cervical vertebra from that of the bird. 



