Page:Quarterly Journal of the Geological Society of London, vol. 26.djvu/269

1869.]

The objected to the term Reptiles being applied to Amphibia, from which they were totally distinct. He questioned the safety of attributing the jaw to Baphetes, of which no lower jaw had been previously found.

Mr. remarked that the Cephalaspis differed materially in its proportions from any in either the Russian or the British rocks.

examination lately made by Mr. Davies, Sen., of the fossils presented to the British Museum last year by J. C. Mansel, Esq., has led to the identification of a large crocodilian head with the Saurian the lower jaw of which I described last session, and identified with Dakosaurus maximus of Quenstedt. Covered with matrix, this head had been previously put aside as Pliosaurian, other Pliosaurian remains having been presented to the Museum by the same munificent donor; but now that its identity has been correctly established, a short account of it seems to be a fit sequel to my last paper.

The general agreement of their dimensions, and their discovery near together (in a reef exposed at low water in Kimmeridge Bay), make it highly probable that this head and the lower jaw both belonged to one individual.

The considerable part of the head discovered by Mr. Mansel includes the back of the skull, the left upper temporal arcade, and the entire snout. The extremity of this latter is completed by the præmaxillæ figured in the last number of our Journal, the sutures in which so exactly coincide with those in the broken end of the snout that there cannot be any doubt of the correctness of this restoration.

The shape of the head is a long triangle; its sides converge from the occiput to the end of the snout, with a slight outcurve of the temporal arcade, a moderate incurve in front of the orbits, and a very slight inbend behind the nostril. Its base, a narrow occipital crest, slopes downwards and outwards from a lofty sagittal crest to the truncated mastoid angles.

The skull has the characteristic narrowness of the temporal region, the extremely large crotaphite foramina, the lofty sagittal crest, and the lateral orbit which mark Geoffroy Saint-Hilaire's subgenus Steneosaurus.

The sagittal crest, in its present mutilated state, rises two inches above the brain-cavity; a coarse diploë fills the interspace. The