The Kimmeridge snout has the same oval, laterally compressed terminal nostril in which the Honfleur "tete a museau plus court" differs from the Gangetic Gavials and the Teleosaurs ; and taken by itself, I think its specific identity could scarcely be doubted by any one who compared it with Cuvier's figures 6, 7, pl. viii. ; while if, when making the comparison, the strong resemblance of the lower jaw is borne in mind, the conviction that the individuals are specifically identical becomes irresistible.
That Cuvier rightly matched the jaws of his "tete a museau plus court" is now established by the conjunction of the jaws in this Kimmeridge fossil, which affords us another instance of the wonderful sagacity of this master in paleontology. The occurrence of amphicoelous vertebrae, and one of these probably the 5th thoracic, together with these Kimmeridge jaws is important, because it removes all doubt which of Cuvier's vertebral systems belongs to the " tete a museau plus court," and makes it evident that it is the " systeme concave "*.
III. The Kimmeridge crocodilian is identical with Dakosaurus of Quenstedt.
Inasmuch as the genus Dakosaurus was founded on teeth only, it is with those that the comparison between it and our Kimmeridge Saurian must be made.
Quenstedt's description of the teeth of Dakosaurus in 'Der Jura,' Tubingen, 1858, p. 131, was drawn from six teeth in a piece of jaw, probably the lower, 1 foot long ; they are two-edged, serrated, unequally convex, subincurved, subretrocurved and implanted. He adds that he had formerly† described these teeth under the provisional name of Megalosaurus ; and he points out that they differ from genuine Megalosaurian teeth in the greater compression, coarser serrature, and more sickle -like curvature of the latter. Further, Quenstedt identifies with his Dakosaurus the large tooth which Prof. Plieninger described in the ' Wurttemb. Jahresheft,' 1846, and represented in fig. 2, tab. 3. of this work under the name Geosaurus maximus, a name which Plieninger withdrew in 1849, on additional evidence that differentiated his Saurian from Sommering's acrodont Geosuar‡.
Our Kimmeridge teeth agree in every essential particular with those of Plieninger's Geosaurus maximus, and with those of Quenstedt's Dakosaurus. Plieninger's figures (fig. 2, Taf. 3), which are
- For a precis of the various views which have been entertained by later
writers I must refer to Pictet's ' Paleont.' and Brown's ' Lethaea.' In face of the positive facts that " des vertebres de la deuxieme espece (i. e. systeme concave) etaient petrees daus le meme morceau que la grande machoire inferieure, ce qui pourrait aussi engager a croire qu'elles venoient du meme individu " (Ann. du Mus. t. xii.), it is very remarkable that Cuvier should have allowed speculation to prevail, and have assigned to this jaw the " systeme convexe en avant."
† Cf. " Flotzgebirg. Wurttemb." p. 493 in Handb. der Petrefakt., tab. 8, fig. 4.
‡ Cf. Wurttemb. Jahresheft, p. 252, tab. i. f. 7, 1849-50.
