1914] The Ottawa Naturalist. 153 



The lachrymal forms the greater part of the front rim of 

 the orbital opening, and meets the jugal below. It is injured 

 anteriorly, and the frontals are not preserved. The postfrontals 

 between the supraorbital horn-cores form a flat surface which 

 slopes downward in front but descends much more rapidly 

 behind. The tumidity of the surface behind the horn-cores 

 merges into the broad anterior elevation of the squamosals. 

 The suture between the postfrontals is not visible in front, but 

 in the midline of the postfrontal surface there is a long, narrow 

 fontanelle which extends back from a point in line with the 

 posterior half of the horns to the anterior end of the raised 

 parietal platform which enters into the formation of the 

 posterior margin of the fontanelle. This opening is rounded 

 behind and in front, and comes to a sharp edge 

 at the margin. Within, the excavation has a smooth floor and 

 extends to each side for some distance beneath the postfrontals. 



Three smooth prominences occur in line on the broad 

 anterior ridge of the squamosal, and in continuation there is 

 an indistinct one in advance of the postfrontal suture, the tumid 

 surface behind the supraorbital horn-core being one of the series, 

 and the horn-core itself may be considered as the anterior 

 culmination. In the midline of the coalesced parietals two 

 obscurely marked elevations of a like nature occur in advance 

 of the median shaft. 



The coalesced parietals form the floor and side walls of the 

 posterior end of the postfrontal fontanelle, to what extent is 

 not known, but the parieto-postfrontal suture is probably at 

 the anterior end of the narrow surface of bone seen in the 

 superior vie w of the skull separating the fontanelle from the sup- 

 rat emporal fossa. This entry of the parietal into the formation 

 of the postfrontal fontanelle occurs in both Styracosaurus and 

 Centrosaurus. 



The mouth or opening of the supratemporal fossa is rather 

 narrow, and in coming from beneath the postfrontal it deeply 

 undercuts the parietal platform and the squamosal, more 

 especiallv the latter. The whole of the floor of the fossa at its 

 mouth is supplied bv the parietal, the squamoso-parietal stiture 

 being at the extreme outer limit of the floor. The sharp over- 

 hanging edge of the mouth of the fossa is continuous in its curve 

 and is contributed to by the parietal, squamosal and post- 

 frontal, to a less extent by the last than by the other two 

 elements. In advance of the parietal platform the surface of 

 the bone drops to a slightly lower local level, leaving the anterior 

 termination of the platform sharply defined. 



The lower jaw is strong and robust. The depth of the 

 ^ dentary at its midlength, measured from the inner alveolar 



