from the Northumberland Coal-field. 185 



broken off diagonally backwards from left to right ; and pos- 

 teriorly the specimen is broken away in a parallel diagonal 

 line a little behind the great vomerine tusks ; so that on the 

 right side nearly the whole of the maxilla is present ; on the 

 left the fracture passes close to the base of the large vomerine 

 tusk, consequently the maxilla of this side is almost entirely 

 wanting. In form the specimen is rhomboidal, being diago- 

 nally broken across before and behind ; the sides are perfect ; 

 it measures lengthwise 3| inches, in breadth 6 inches. 



Both the dorsal and palatal surfaces have been cleared of 

 the matrix, a work of much care and labour ; and though the 

 parts are crushed and distorted, many of the characters are 

 well preserved. The sculpture of the bone on the dorsal sur- 

 face is distinctly displayed, and is of the usual Labyrinthodont 

 character, resembling very closely that of Pteroplax ; but the 

 pits or depressions are less regular, and the surrounding ridges 

 are rough and much broken up. The frontal bones are broken 

 away before and behind, but the greater part of them is evi- 

 dently present; they are considerably elongated, and are a 

 little expanded in front. A triangular bone, with its apex 

 forward, is interposed on either side between the frontals and 

 the maxillae ; these bones are probably the postfrontals, or 

 they may be the prefrontals and the postfj-ontals in combina- 

 tion. On the left side a fragment, probably of the nasal bone, 

 is wedged in in front, between the anterior extremity of the 

 frontal and the maxilla. The sutures are represented by wide, 

 smooth, depressed lines, but, with the exception of those of the 

 frontals, they are not very easily determined. 



The other side of the specimen exhibits the roof of the 

 mouth, but the bones are so much crushed and broken that it 

 is impossible to make out their forms and limits. Suffice it 

 to say that, a little in front of the great vomerine tusks, there 

 is, on each side, a large deep depression (which two depres- 

 sions are undoubtedly the anterior palatal foramina), and that 

 immediately behind and towards the outer margin of the right 

 vomerine tusk a circular depression, upwards of half an incli 

 in diameter, indicates the position of the right posterior naris. 



The teeth belonging to the fragment are nearly all present ,• 

 but many of them are broken down and displaced, and only 

 a few retain their apices. The two great vomerine tusks are 

 not much disturbed ; that on the right side stands erect, but a 

 large portion of the crown has disappeared. It is placed 

 somewhat nearer to the maxilla than to the central line of the 

 skull, and is not very far from the anterior margin of the spe- 

 cimen ; what remains of it is f inch in height, and it measures 

 across the widest part of the base \ inch. The left vomerine 



