MAXILLARY BONE OP A NEW DINOSAUR. 443 



shape is seen in the Rhinoceros, in which the pre maxillary similarly 

 joins a narrow anterior border of the maxillary, and the relations 

 of the bone are such as might occur in a Dinosaur. 



EXPLANATION OF PLATE XX. 



Maxillary bone of Priodontognathus. Three fourths natural size. 



Fig. 1. External aspect. 



2. Internal aspect. 



3. Alveolar aspect of the same bone, showing the tooth-sockets and the 



dental foramina. 



4. Superior aspect of same bone, showing the semicircular outer nasal wall . 



a, bevelled margin articulating with tbe premaxillary bone ; b, posterior zygo- 

 matic process ; c, ascending nasal process dividing the nostril in front from the 

 orbit of the eye behind ; d, dental foramina showing several successional teeth ; 

 e, canal for blood-vessel and nerve ; /, fractured surface from which the palatal 

 portion of the bone is broken away ; g, sockets for the teeth ; h, matrix. 



Discussion. 



Mr. Etheridge expressed his regret that the locality of this in- 

 teresting fossil was unknown. The Pecten was not P. vagans, but 

 P. fibrosus. He thought that the block containing the fossil was 

 either Calcareous Grit or Coral Rag, and that it had probably been 

 obtained as a fragment on the sea-shore. If so, it would be salt to 

 the taste. In this case there were only two points from which it 

 could have come, namely, the Yorkshire coast and Hastings. 



Mr. Jtjdd remarked that Mr. Sorby had made a microscopic in- 

 vestigation of the structure of the Calcareous Grit of the Yorkshire 

 coast, and suggested the possibility of ascertaining the locality from 

 which this specimen had been derived by an examination of the 

 microscopic characters of its matrix. 



Mr. Seeley, in reply, said that he did not detect the presence of 

 salt in the stone. The Pecten probably was the form described as 

 P. fibrosus : but he regarded P. fibrosus and P. vagans as identical. 



