THE SKULL OF PALEORHINUS 135 
At its anterior extremity this surface is not over three-eighths inch 
wide, but at its widest extension, at the thirty-fourth tooth, it is one 
inch across. Back of the last tooth the bone narrows abruptly. About 
opposite the posterior end of the premaxilla the dentiferous surface 
of the maxilla begins to be depressed below the palate and this depres- 
sion increases until opposite the rear teeth it is about one inch. Just 
behind this region a rounded buttress-like process passes down the 
inner surface of the maxilla nearly to the edge of the jaw. It may be 
that the jugal forms the upper part of this buttress, but this is not 
known. The process is pierced by a small foramen which extends 
nearly parallel to and about one-half inch above the edge of the jaw. 
The purpose served by this foramen is uncertain. 
Between the twenty-eightb and thirty-third teeth the maxilla bears 
an obtusely triangular extension which les perhaps three-fourths 
inch above the dentiferous margin and enters into the lateral portion 
of the bony palate. 
Palatine.—The anterior limit of this element is not positively 
known, but its relations with the premaxillz are believed to be about 
as indicated in the figure. Posteriorly it widens as the maxilla 
narrows and reaches its extreme width—one and one-half inch— 
opposite the posterior limit of the internal nares. Behind this point 
it tapers gradually, chiefly by being cut away on the outer edge, and 
leaves the maxilla more and more as it passes backward. Its extreme 
length is probably six and one-half inches. It is united with the 
maxilla along the outer edge back to the line of its greatest width, 
but from here to the posterior end the two are separated by the trans- 
verse (ectopterygoid) with which the palatine unites by a roundly 
serrate suture. The two bones separate slightly about midway 
along the suture, and leave the narrow palatine vacuity between them. 
Along the inner margin the palatine unites with the pterygoid as far 
forward as the internal naris, whose entire outer margin it is believed 
to form. It probably overlaps the maxilla somewhat in its anterior 
portion as is apparently true of the European belodonts. 
The palatines lie at a somewhat lower level than the pterygoids 
and so leave between them a cavity in the palate in which lie the 
pterygoids and vomers. The inner edges of the palatines are turned 
vertically upward to unite with the pterygoids. It is probably the 
