The elements of the skull are all so firmly united that they can not be distinguished. There are no indications whatever of a horny sheath enclosing the jaw, and it is improbable that the covering of these parts was essentially different from that in the slender jawed Pterodactylidae. In texture, the maxillaries are fine-grained, and wholly without the vascular foramina found in the corresponding bones of birds. The bones are composed of two thin and firm plates, separated by cavities which are bounded by irregular walls of bony tissue. In the compression from which all the Pterodactyl bones have suffered more or less, the greater resistance of these walls has caused irregularities upon both the outer and the inner surfaces. At the borders of the bones, where the thickness has been greater, the roughening is not observed.
Seen from above, the skull is narrow, as stated by Marsh; but, contrary to his statement, there is not a sharp ridge extending along the upper border. This border is obtuse and rounded, and in the frontal region, flattened. The sagittal crest is large, but not nearly so large as it is figured by Marsh, the restored outline of whose figure is undoubtedly wrong. The texture of the bone forming the crest is materially different from that of the remaining bones of the skull. The bone is more roughened, and less firm. There is a well-developed ring of sclerotic ossifications. In the specimen figured, the separate plates measure from six to eight millimeters in diameter. They were not imbricated, as in the Pythonomorpha, but have a similar dense texture. There is a superior temporal arch, bridging over a small opening leading downward to the inferior temporal fossa. The following measurements will give the principal dimensions of this specimen.
| Length from tip of premaxillary to occipital condyle | 680 | millim. |
| Extreme length of skull | 780 | |
| Extent of crest beyond orbit | 145 | |
| Greatest diameter of orbit | 65 | |
| Antero-posterior diameter of nasal opening | 135 | |
| Length of quadrate | 120 | |
| Width of lower jaw at articulation | 22 |
Pubis.
In a previous paper on the anatomy of Pteranodon,[2] I stated that I had never seen the so-called “prepubic bones.” Since that time, however, an excellent specimen of them has been discovered among our material. The specimen of which they are a part consists of the larger portion of the skeleton, and is perhaps conspecific with the one to which the described pelvis belongs. The figure given herewith will convey a good idea of their shape. The bones of the two sides are firmly co-ossified, and have been pressed nearly flat; the figure represents them as they are spread out in one plane. The bone is very thin throughout, with a slight thickening at the ischial (a) attachment only. Lying contiguous with the anterior projection, is a slender ventral rib (b). It is possible that the curvature of this bone may be inward, rather than outward.
FIG. 1.
This peculiar structure of the pubis (I believe it represents the pubis, and not the prepubis), seems to be quite similar to that which obtains in the genus Rhamphorhynchus, and, perhaps also, in Pterodactylus suevicus (Cycnorhamphus Seeley), and very different from that found in other species of Pterodactylus.
The principal measurements of the above described specimen are as follows:
| Antero-posterior expansion | 40 | millim. |
| Length of symphysis | 14 | |
| Expanse of the united bones, as flattened | 90 | |
| Width of ischial process | 11 |