The only Mammal which shows any near approximation to this brain is the _Ornithorhynchus_, in which the cerebellum is very small, but the cerebrum is not so well rounded in front. The form approximates to the brain in Man. But with Birds the resemblance is so close--with the owl and the goose--that there is no character to distinguish the brain of the fossil animal from those of the recent ones. A section of the cerebrum in this specimen entirely corresponds with a section of the brain-cavity in the second skull described, as does the backward extension of the cerebrum with the extent of the cerebral cavity, and the narrow cerebellum with the narrow channel parallel to the walls of the foramen magnum, as in _Gallus domesticus_ and Birds. The front of the brain corresponds with the cast of the front of the cerebral lobes taken from the Ethmo-sphenoid mass. Thus the specimens agree among themselves, and prove the Pterodactyle to have had a brain indistinguishable from that of a Bird. And when it is remembered how distinctive this kind of brain is, and that it approximates rather towards the higher Mammals than towards Reptiles, the fact attains unusual importance in determining the Pterodactyle's place in nature. ?NEURAL ARCH OF SACRAL VERTEBRA, ?VOMER. Pl. 12. Frontal(?) Owen. _Palæontographical_, 1859 Pl. 4, fig. 6, 7, 8. Case. Comp. Tablet. Specimen. =J= _c_ 10 1-3 In 1859 Prof. Owen described with doubt as the Frontal of Pterodactyle, a symmetrical bone. A smaller but more perfect specimen has since been obtained for the Woodwardian Museum; and a fragment of intermediate size is in the rich collection of the Rev. T. G. Bonney. From the descriptions already given it is impossible for it to be the frontal. There is no proof that it is a skull bone. If of Pterodactyle the compressed lateral spaces could only be part of the nasal passages, or the impressions of a palatine or pterygoid articulation. And as the external surface of every specimen is keeled, and as the palatal surface of the upper jaw of every known Greensand Pterodactyle is keeled, and as the concavities slightly converge to the keel, it might be a bone from the under side of the head,--the vomer.