12 FOSSIL REPTILIA OF THE 



contracted in the middle ; the fore part of the under surface is a little produced ; the 

 baclv part almost flat between the rudimental parapophyses ; the shallow anterior 

 concavity has resumed its transversely eUiptical shape, and the hinder convexity is 

 defined below by a shallow groove connecting the parapophyses. There is no 

 pneumatic foramen, unless a small hole on each side the hinder outlet of the neural 

 canal have served as such ; the neural arch is long and low, quite one piece with the 

 centrum, which extends beyond it posteriorly. It sends off short, obtuse zygapophyses 

 before and behind, those in front extend beyond the cup of the centrum ; the sur- 

 faces on those behind look downward and backward. The base of the spine is coex- 

 tensive with the summit of the arch, but is narrow. The neural canal is much 

 contracted. There is no indication of a haemal arch, either by articular or fractured 

 anchylosed surfaces. The diameter of the middle of this vertebra is 6 lines. 



The caudal vertebra next in size measures 1 inch 5 lines. The base of the neural 

 spine begins 2 lines behind the fore part of the arch, but terminates nearer the hind 

 part ; the nerve-grooves notch the hinder zygapophyses. 



Three more slender caudal vertebrae present each a length of 1 inch 3 lines ; the 

 diameter at the middle is 5 lines in one, 4 lines in a second, 3^ lines in the third 

 vertebra, showing that they become more slender without losing length. A caudal 

 vertebra 3 lines across the middle appears to have been nearly an inch in length ; 

 but both extremities are injured. 



Frontal Bone (?) 



As it is probable that the median symmetrical portion of bone (Tab. IV, figs. 

 6, 7 and 8) may belong to the cranium of one of the large Pterodactyles from the 

 Upper Green-sand, its description follows that of the vertebrae. 



It is 2 inches 4 lines long ; 1 lines across its broadest part ; 1 inch 2 lines in 

 depth, to the surface where the piece has been broken away ; the sides present a 

 smooth concave plate of bone (fig. 6), as if the piece had been nipped between a 

 finger and thumb, but quite symmetrically ; the surface, which, on the supposition 

 that those smooth concave facets were inner walls of the orbits, would be the upper 

 one, and due to the frontal bone, is gently convex in the direction of its length, and 

 has a median longitudinal ridge, which expands and subsides near the end most pro- 

 duced beyond the lateral depressions. I have observed a similar median ridge or 

 rising upon the single frontal bone of the Alligator lucius, between the orbits, and 

 upon the double frontal, supporting the median suture, in the Rhynchocephalus lizard of 

 New Zealand, There is also an indication of such a median ridge in the figure of 

 the cranium of Pterodactylus suevicus, in Professor Quenstedt's Memoir on that 

 species (4to., Tubingen, 1855), 



