16 Field Columbian Museum — Geology, Vol. II. 



part, where the surface is nearly smooth. The posterior teeth are 

 much smaller, as already stated, and are much more closely placed, 

 their length varying from six to twelve millimeters. 



The united parietals form a high, thin, vertical plate of bone, 

 convex in outline, about fifty millimeters in height in the middle, and 

 only three or four in thickness at the margin, and extending nearly as 

 far forward as the pineal foramen. Posteriorly, the sides extend 

 downward and outward into a broad flattened process for union with 

 the upper ramus of the squamosal. The suture, which is clearly 

 apparent, runs downward and outward to the free margin of the 

 parietal on each side, beginning in front of the posterior thickened 

 bar of the squamosal. Anteriorly this free margin of the parietal is 

 continued outward, like the eaves of a roof, to the posterior part of 

 the orbit, where it is somewhat roughened ; it turns upward here 

 rather abruptly. About twenty millimeters above- this angle, separated 

 by a concave space, is the massive projection for the epipterygoid. 

 This bone has been broken away from its attachment on each side, 

 and separated for a short distance, leaving a jagged fracture, without 

 indications of suture. The upper margin of this thickened epiptery- 

 goid protuberance is continued by sutural union with the postfrontal. 

 A little in front of the parietal foramen, the bone narrows to a width 

 of four or five millimeters, blended with and continued into the frontal, 

 which continues forward to the premaxillary, under which it disap- 

 pears. The sutural union for the postfrontal is well marked on the 

 right side, beginning a little back of the pineal foramen and running 

 downward, outward and backward to the upper margin of the epiptery- 

 goid protuberance. Internally the parietals form a broad roof, to 

 which is attached, rather far forward, by distinct, oval, obliquely 

 placed, V-shaped articular surfaces, the paired supraoccipitals, which 

 do not reach quite to the lower free margin of the parietals on 

 each side. 



Anteriorly,, as already stated, the frontal (?) continues, without 

 the slightest indication of a suture with the parietals, forward for forty 

 millimeters or so more, as a narrow, flattened surface above, distinctly 

 divided by a median suture, to the upper end of the facial processes 

 of the premaxillae, which articulate on the outer side of the slender 

 projection, overlapping the upper surface. How much further the 

 bones continue I can not say, but evidently as far forward as the 

 anterior end of the orbits. On the right side, the " postprefronto- 

 nasal" has been macerated away, so that its relations are clearly 

 marked. Below these bones are broader, continuous on each side 

 with the free margin of the roof, as already described. The rostrum 



