[Footnote 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
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.
The _parietal region_ is convex from below upward, the lateral parts converging towards the crown, which however presents a broken and worn surface. From side to side the squamosal and parietal bones are concave, owing to the extended occipital crest behind, and the rapid widening of the skull in front caused by the large size of the brain.
In _front_ is seen a section of the brain-cavity. It is very like in form to the two halves of a pear put together side by side with the stalk downward. I have removed some of the phosphate of lime from the brain-cavity, and although it has not been excavated to the cerebellum, the great depth of the brain is well seen, and the convex character of the cerebral lobes, between which a crest of bone descends mesially as in the ethmo-sphenoid mass next described. At each of the lower outer angles of the brain, extending into the cancellous brain-walls to the outermost film, is an ovoid convexity, covered with a thin film of bone. They entirely correspond with the optic lobes, being in exactly the same position as in birds, only relatively rather small. Underneath the optic lobe on the outside is a small concavity, apparently the articulation for the quadrate bone. The basi-sphenoid mass below the brain is of considerable height, the upper half flat and smooth, the lower half fractured and cancellous.