310 Mr. D. M. S. Watson on 



passage and by a deep but very narrow median ridge 

 partially divides the posterior nares ; its lateral borders are 

 joined hj the palatines, and further back by the pterygoids ; 

 the sutures separating these bones from the vomer run along 

 anteriorly just below and within the summits of the rounded 

 ridges which mark out the median area of the palate ; 

 posteriorly the sutures cross these ridges and are lost. 

 The dorsal surface of the vomer has a strong but very 

 narrow median ridge, which is directly continuous with the 

 ridge of the front part of the basisphenoid. 



Quadrate (figs. 3 & 7). — The right quadrate is well 

 exposed from in front, below and partly from behind. It 

 consists of a thin vertical plate received in the triangular 

 hollow on the front face of the squamosal. This plate has 

 a thickened lower border which is the actual articulating 

 surface ; it is marked by a low and obscure ridge towards the 

 outer side. 



This plate carries two backwardly directed processes, each 

 a thin vertical plate, the outer, which is situated very near 

 to the extreme outer edge of the whole bone, being the 

 larger. These two processes are received in the two notches 

 of the articular edge of the squamosal. A fracture during 

 development shoMcd conditions suggesting the presence of a 

 small foramen piercing the quadrate from back to front, 

 just above the lower margin and between the two posterior 

 processes. 



A specimen described later in this paper shows that this 

 quadrate is incomplete, a very thin inwardly directed process 

 being lost, certainly before fossilization. 



Frontal (fig. 1). — The frontals meet one another in a long 

 median symphysis running forward from the pineal foramen. 



Each frontal is united by suture with the postfrontal and 

 sends back a narrow process between the thin film of 

 parietal in advance of the pineal foramen and the middle 

 line. 



The frontal also articulates with the prefrontal and nasal 

 and does not enter into the orbit. The under surface is 

 not exposed. 



Postfrontal (figs. 1, 2, & 5). — The postfrontal forms part 

 of the postorbital bar, which is massive and has a flattened 

 upper surface with a distinct groove leading inwards to the 

 depressed area of the frontals. The lower face of the post- 

 orbital bar is rounded. 



