SKELETON OF PHOEOEHACOS INFLATUS. 61 



possible to make out the extent and relations of the facial parts of the maxilla?, and it 

 is therefore uncertain what share, if any, they may take in forming the boundary of 

 the nostrils. 



The premaxillce no doubt form the greater part of the enormous beak, but their 

 exact boundaries are not distinct. Superiorly they send out fused nasal processes, which 

 form at least the upper part of the high bar of bone between the nostrils and perhaps 

 extended to the frontals. Anteriorly the bodies of the premaxilla? form the high laterally- 

 compressed anterior section of the beak, the tip of which forms a downwardly-directed 

 hook, about 3 - 5 cm. long and small compared to the bulk of the whole beak. From 

 the sides of the base of this hook a pair of parallel ridges run back on to the palate ; 

 their posterior portion is separated from the tomium by a deep groove, into which the 

 edge of the mandible fits when closed ; on their inner side also there is a deep channel, 

 divided by a median ridge, which just behind the decurved hook rises into a prominent 

 tuberosity, at first described as a tooth. 



The cutting-edge of the beak forms a double curve ; it commence a little behind the 

 point and first forms a strongly convex, prominent edge, sharp in front, but more 

 rounded behind ; posteriorly it is very slightly concave, and is a continuation of the 

 line of the lower edge of the jugal arch. The anterior convex portion is no doubt 

 formed by the premaxillse ; the posterior is maxillary. In the premaxillary region the 

 narrow palate is closed, except. for a few small median foramina, and is deeply 

 concave from side to side. 



The beak, as a whole, is very deep from above downward, strongly compressed 

 laterally, and its whole surface covered with angular and vascular impressions, which 

 indicate that in life it was covered with a very thick horny sheath ; the whole must have 

 formed an extremely formidable weapon, whether for attack or defence. 



The upper portion of the cranial region of the skull is much flattened (Plate XV. 

 fio-. 2). Posteriorly it is greatly constricted by the great temporal fossa?, which are 

 separated in the middle line by an interval of about 12 mm. only. In front of these 

 it widens out and reaches its greatest width at the level of the postorbital processes. 

 In front of these it again narrows, and anteriorly the frontals join the nasals, but their 

 limits are not very clear. The orbital borders of the frontals have thiok roughened 

 edges, and probably the great supraorbital plates of the lachrymals, which now lie 

 slightly below the level of the frontals, may, in their normal condition, have united 

 with them throughout their whole extent ; but, since their position is symmetrical 

 on the two sides, it is possible they may be in their natural position. As already 

 mentioned, this depression of the supraorbital plates gives the skull, when looked at 

 from above, the appearance of having possessed deep supraorbital fossa?. 



TJie Palate (Plate XV. fig. 1). — The most important result of the careful removal 

 of the matrix from the skull is that the structure of the palate is completely revealed, 

 the bones being perfect and very little displaced. The taxonomic importance of this 



