Page:Quarterly Journal of the Geological Society of London, vol. 27.djvu/127

1870.]

fossils were collected by the late Captain Strickland, and forwarded by Mrs. Strickland, for examination and description, to Mr. Busk, who intrusted me with them for this purpose, informing me at the same time that they came from Gozo, the Gauda of Strabo, an island adjoining Malta, reputed miocene.

As one of the fossils indicates, I believe, a new crocodile, and the other, if Gozo be really miocene, if the jaw actually came thence, and if my determination should prove correct, shows the survival of an Ichthyosaurus to a much later period than that of the upper white chalk, the most recent formation in which any remains of this genus have yet been found, they seemed to me worthy of being brought under the notice of this Society.

The fossil which I venture to refer to the genus Ichthyosaurus is the symphysial part of a long slender mandible. The front end is wanting; and the rami have also been broken off just behind the symphysis. In its present mutilated state it measures 9 in. long, 1⋅2 transversely in front, and 2⋅1 at the posterior limit of the symphysis. Its outer surface is transversely gently convex, smooth, and finely wrinkled longitudinally. The upper surface presents a smooth narrow median tract, in front greatly convex transversely, behind slightly concave in the same direction, mesially divided by the symphysial suture, in which posteriorly the splenial element is discernible. This is bordered externally by a line of shallow tooth-pits, separated by low transverse ridges, the outer ends of which ascend a short distance on a low parapet formed by the slightly higher outer edge of the dentary bone. Most of the pits are empty; and their smooth surface shows the absence of any firmer bond of union than the gum between the teeth and the mandible.

The teeth are conical, the crown is slightly compressed, its transverse section elliptical; the fang is simple, of a bulbous figure, its exterior is smooth, its base slightly contracted and rounded. The principal tissue is a simple tubular dentine, in the crown covered by a thick enamel, while in the fang it is enveloped by a stout capsule of cementum. A pulp-cavity rises through the fang for some distance into the crown. A minute plug of spar fills its upper end; and its lower end encloses a little mass of osteo-dentine, which is continuous, through the contracted basal end of the cavity, with the external cementum.