Page:Quarterly Journal of the Geological Society of London, vol. 34.djvu/478

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remains from the Corallian Rocks are so rarely to be obtained, that neither in the British Museum nor in the collection of the Geological Survey in Jermyn Street are there to be found more than a few isolated teeth from this horizon. Such being the case, I was led to attach some little importance to the discovery of the remains of a Crocodilian (?) jaw in the beds of this age at Weymouth; and as the specimen possessed certain peculiarities, it seemed desirable that some notice of it should be placed upon record. I have therefore ventured to lay before the members of this Society the following description of the fossil.

The general appearance of the specimen, which I believe to be a portion of a lower jaw, is shown in figure 1; it measures about 11 inches in length. Its present dilapidated condition is due partly to weathering before it was discovered, and partly to the friable nature of both the bone and the matrix, which added much to the difficulty of detaching it from the mass of rock in which it was imbedded. When first found, the upper or alveolar margins were imbedded in the matrix, and the lower parts had been so far denuded as to expose the alveolar cavities, and in some of the anterior ones parts of the teeth were still to be seen. A considerable part of the hinder end of the jaw is wanting. The right ramus has been broken across at c, and is thrown about a quarter of an inch outwards from its natural position. So much of this ramus as is preserved contains the remains of twelve alveoli; the anterior one, which is nearly obliterated, passes almost directly forwards and is close to the symphysis, showing clearly that the tooth which it contained was the anterior one of this side of the jaw. A fragment of this tooth is still preserved, but not sufficient to enable one to judge of its original size. The 2nd, 4th, and 5th alveoli also contain portions of teeth, which, it is evident, were naturally directed very obliquely outwards and forwards. The remaining seven alveoli are smaller and have all lost their teeth.

The left ramus is so far broken away as to leave only the 1st and 2nd alveoli: but there are the remains of twelve or thirteen others; so that there is direct evidence of its having possessed fourteen or fifteen teeth. Parts of the 3rd, 4th, and 5th teeth are still retained in their sockets. The fragments of bone lying behind and in the general direction of the right ramus are probably broken pieces of one or more of the other elements of the jaw.

The fragile nature of the specimen rendered it very hazardous to attempt to clear away the matrix from the upper surface; but this