398 E. T. NEWTON ON A CROCODILIAN JAW FROM 



23. Notes on a Crocodilian Jaw from the Corallian Rocks of Wey- 

 mouth. By E. Ttjlley Newton, Esq., F.G.S., of H.M. Geo- 

 logical Survey. (Read February 6, 1878.) 



[Plate XVI.] 



Crocodilian 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 desir- 

 able 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 



II 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 out- 

 wards 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 con- 

 tain 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 



