Page:Quarterly Journal of the Geological Society of London, vol. 26.djvu/270

 foramina have a squarish outline, and from back to front they measure nearly six inches. The temporal arch is proportionately long and strong; the occiput is broad and low; the angular crest already noticed forms its upper limit; its lower border is thin and nearly straight. This and the greater part of the posterior surface appear to be formed by an outward extension of the exoccipital to the mastoid and quadrate bones. The surface, generally flat, is crossed on the level of the foramen magnum by a horizontal ridge, which makes an acute angle with the outer end of the occipital crest. Between this ridge and the crest the surface is depressed and slightly overhung by the latter. Beneath the outer end of the ridge is a deep hollow. The foramen magnum is an ellipse; its horizontal axis measures 1·1 inch, and its vertical axis ·8.

The occipital condyle is broken off, as is also the articular end of the quadrate bone. Of the orbits, only the front and upper part of the left one remains; its lateral position gives its opening an outward direction; its anterior border seems to have scarcely risen above the level of the surrounding parts. A furrow probably marks of the lachrymal from the præfrontal bone. Between the orbits, the broad forehead, now very mutilated by fractures, appears to have been gently convex. The sutures are here too indistinct to allow me to speak with certainty of the forms and limits of the bones composing this region.

The snout is shorter than that of the Honfleur Gavial "tête à museau plus court." A pair of large triangular bones united by a mesial suture 9 inches long, descend from the forehead to the middle of the snout, forming a great part of the upper surface in this situation. Their posterior limit is not accurately determinable. It appears to be invaded by a descending process of the prefrontal. Their outer border is conterminous behind with the maxillary bone. In front they form conjointly a broad wedge. These bones evidently correspond in their position and in their relations to the pair of bones lettered a a in the illustrations of the Honfleur Gavials in the 'Ossemens Fossiles,' which Cuvier called nasals. He refers to them in these words:—"On y voit, en a, les extéemités antérieures des os du nez, formant comme dans le Gavial, une pointe précédée par la réunion des maxillaires, b b, qui continuent le tube des narines en avant jusqu'aux intermaxillaires."

The same bones are plainly indicated in a cast of a crocodilian snout in the Museum of the Royal College of Surgeons, described in the catalogue as a cast of the snout of Steneosaurus robustus, presented by Dr. Buckland. Dr. Rolleston, in reply to my inquiry, informs me that these bones are also shown in a cast of the Honfleur (Geneva) Steneosaur in the Oxford Museum, and that the relations of the bones in the upper surface of a Steneosaurian skull from