So that it must be asserted that the differences of these Pterodactyles from Lizards are so wide as to preclude comparison.
With the Crocodile, in which the cranial bones are massive, and the quadrate bone firmly packed in the skull, comparison would be no less difficult.
The Delphinidæ, in both the form of the jaws and of the back of the head, give some support to Wagler's fancy, in putting the Pterodactyle into his curious creation, the Gryphi[T]. But in the porpoises the parietal bones form as narrow a band as they do in the Duck; and are quite unlike the bones here described. In the Dolphin the two condyles almost unite into one semicircular condyle (in young specimens), owing to the enormous development of the ex-occipitals, which almost if not entirely exclude the basi-occipital from the foramen magnum. The dolphin moreover has no quadrate bone. But notwithstanding the absence of a division into occipital and parietal segments, the form and arrangement of the bones in the skull of the porpoises approximate more to the Cambridge Pterodactyles than is the case with Lizards.
[T] The Gryphi are a class of animals intermediate between Birds and Mammals according to Wagler, and including Pterodactyles, Ichthyosaurus, Plesiosaurs, Ornithorhynchus, and Myrmecophaga.
But with Birds the correspondence is so close that it would be difficult to discover differences. That one of the condition of the occipital bone seems to be the most important; another is, that from the relatively smaller size of the cerebellum the parietal bones appear to cover a larger part of the cerebrum; and a third is the strong triangular condition of the sphenoid in front of the sella tursica. With these exceptions there is nothing to distinguish the fossil described from the cranium of a bird.
| Case. | Comp. | Tablet. | Specimen. |
| J | c | 8 | 2 |
Back of another Cranium.
[Pl. 11. fig. 1, 2.]
Another cranium has occurred which must be referred to a different genus. Its preservation is less perfect, but it similarly exhibits the occipital and parietal segments of the skull. All the bones are blended together without a trace of a suture.
The occipital region is flat. Its outline is not defined owing to the extent to which the sharp crest, in which it terminated outwardly, has been broken away. The occipital condyle is broken off. The foramen magnum is of an ovate form—flattened at the base. The ex-occipitals at its sides are impressed as though from contact with the neurapophyses of the atlas. Mesially, over the foramen magnum is a vertical elevated crest (now rubbed away), which may have given attachment to a bone like that post-superoccipital crest described by Quenstedt in the Pterodactylus suevicus. The occipital region makes a great angle with the flat basi-temporal region, as in birds.