Page:Quarterly Journal of the Geological Society of London, vol. 25.djvu/521

1869.] spherical articular head, below which is a slight swelling, which I take to be the traces of a crushed and worn trochanter. The shaft has been much squeezed. All the fractures show that the interior consists of cancellous tissue, which, in some situations, has a very open texture, without, however, there being strictly any medullary canal. The axis is very slightly twisted, much less, I think, than in existing crocodiles. The line of the anterior border of the shaft is convex, and that of the posterior border correspondingly hollow. The distal end is much damaged, but traces of one condyle are recognizable.

These diameters are from back to front; those from upper to under surface are less.

Conclusions. — The conclusions resulting from my examination of the fossil remains of this Kimmeridge Saurian are : —

I. That it is an amphicoelian Gavial-like crocodile.

II. That it is probably identical with Cuvier's 2nd Honfleur Gavial, " tete a museau plus court," to which Cuvier assigned vertebrae of his " systeme convexe ; " Steneosaurus rostro-minor of Geoffroy Saint- Hilaire, 1825 ; Metriorhynchus, Von Meyer, 1830, who reversed Cuvier's disposal of the vertebrae, and gave those of the " systeme concave " to the short snout ; Steneosaurus, Owen, 1841, who adopted Von Meyer's allotment of the vertebrae ; Streptospondylus, Von Meyer, 1847, who returned to Cuvier's association of the opisthocoelous vertebrae with the " tete a museau plus court ; " Metriorhynchus Bronn, 1851.

III. That it is also identical with Dakosaurus, Quenstedt.

IV. That Dakosaurus is probably Cuvier's second Honfleur Gavial " tête à museau plus court."

I now proceed to establish these points seriatim : —

I. That this Kimmeridge Saurian is an amphicoelian Gavial-like crocodile is proved beyond doubt by its bifurcated (anterior) ribs, the long transverse processes of the posterior thoracic vertebrae, the sutural attachment of the neurapophysis to the centrum, the concavity of both articular faces of this latter, the nature of the attachment of the teeth and the manner of their succession, the restriction of the teeth to the symphysial part of the jaw and a very small piece of the adjoining ramus, the relatively long symphysis, and the single undivided terminal nostril.

II. It is probably identical with Cuvier's second Honfleur Gavial, "tete a museau plus court."

In order to make this clear I must first cite briefly those facts relating to the Honfleur Gavials which bear directly on this matter. 2 2