33 



The bony palate terminates behind in an angular notch, formed by the ridges (r, r) 

 before described. The bony palate forms a narrow tract, with parallel lateral borders 

 gently diverging at the fore and back part of the tract, which is very slightly concave 

 transversely: it is perforated by numerous foramina; two long ones, like fissures 

 (Plate XV. v, v), opposite the interspace between the third and fourth molars, seem 

 to represent the post-palatal foramina; there are, also, some large foramina (u, u) 

 between the first alveoli. The extent of the palatal part of the maxillary in advance 

 of these alveoli is about 1 inch to the hindmost part of the premaxillary (22), and 2J 

 inches to the apex of the process (21) articulating with that bone. 



The premaxillaries (Plates XV., XII. fig. 1, and XIII. figs. 1 & 2, 22) have coalesced 

 along the major part of their extent, leaving only a median fissure on their upper 

 surface (Plate XIII. fig. 2, 22), of about 1^ inch in length, at about the same distance 

 from their slightly expanded anterior ends ; at their under surface (Plate XV.) 

 the same fissure is more advanced, and contracts to a few foramina. They form a 

 slender, elongated, subdepressed, four-sided portion of bone, and constitute a singular 

 anterior termination of the skull. 



At the base or back part this portion of bone measures 4^ inches across; the fore- 

 end is 2 inches 9 lines across ; the narrowest part, near this end, is 2 inches 4 lines 

 across ; the vertical diameter is pretty nearly throughout 1 inch 6 lines, but decreases 

 anteriorly. The posterior third of the bone sends upward from its median line a 

 ridge, which enlarges as it approaches the corresponding ridge from the maxillaries, 

 and there presents a smooth and gradually expanding groove at its upper part, for 

 the support of the vomer or its cartilaginous septal prolongation (Plate XIV. fig. 2). 

 Anterior to the median ridge begins the groove which sinks into the fissure, and is 

 then again continued forward as a groove to within an inch of the fore-end of the 

 bone: this part (Plate XV. 22) seems crossed by a rough plate or cap of bone, flat, 

 and about an inch in breadth at its upper part, and there terminating behind, as it 

 does below, in a free margin. 



The under surface of the premaxillary mass (Plate XV. 22) is rather convex antero- 

 posteriorly, as also transversely along its middle third : the groove indicating the 

 primitive suture runs along the whole of this surface, and sinking into its fore-part, 

 opens by two or three foramina into the fissure which is seen on the upper surface. 

 The back part of the under surface of each premaxillary is notched to receive a 

 triangular process of the palatine part of the maxillary (21): the more slender median 

 parts of the notches partly divide the prepalatal or incisive fissure (*), which thus 

 presents the form of a chevron. 



The malar (Plate XII. fig. 1,*) is a singularly developed mass of bone, and has 

 always attracted attention as one of the most remarkable features of the skull, 

 from the period of the earliest notices of the Megatherium. Its bulk and complex 

 shape appear to relate to the unusual share which a modified and largely developed 

 masseter muscle must have taken in the act of mastication. 



