MIOCENE PORPOISES — ^KELLOGG 109 



the upper surface of the maxillary slopes from the premaxillary suture 

 to the alveolar margin, becoming steeper anteriorly as the maxillary 

 decreases in depth, and near its extremity is almost vertical. Near 

 the middle of the rostrum (the 14th alveola counting forward) the 

 dorsolateral face of the maxillary has approximately the same depth 

 as that of the premaxillary, but from this point forward it gradually 

 diminishes in height while the premaxillary increases. The extremity 

 of the rostrum is formed entirely by the premaxillaries. From a 

 lateral view the alveolae are visible for most of the length of the tooth 

 row, the hindermost alveola being located 52 mm. in advance of the 

 antorbital notch. The terminal 100 mm. of the rostrum is bent 

 slightly upward, and the basicranial axis is bent downward from that 

 of the rostrum. 



At approximately the level of the 16th alveola counting forward, 

 a small foramen is located in the premaxillary-maxillary suture from 

 which a shallow groove extends forward about 3 mm. above the latter 

 on the lateral face of the premaxillary and disappears about 55 mm. 

 behind the extremity of the rostrum. On the terminal 160 mm. of 

 both premaxillaries are a number of small scattered nodules about 

 2 mm. in diameter and shallow grooves which suggest that the end 

 of the rostrum may have been covered with close-fitting tough skin. 



The dorsal surfaces of the nasal bones are the highest points on the 

 dorsal profile. From the anterior ends of these bones to and slightly 

 beyond the anterior end of the presphenoid, the premaxillaries slope 

 strongly downward. The depressed maxdlaries, however, slope more 

 gradually from the transverse crest of the supraoccipital to the base 

 of the rostrum. 



On its external border, the supraorbital process of the frontal is 

 rather thin. The anterior angle or preorbital projection is a slight 

 enlargement, about 20 mm. in depth, but the posterior angle or post- 

 orbital projection is prolonged downward, forming a slender process 

 which seemingly did not come in contact with the zygomatic process. 

 The maximum anteroposterior diameter of the left supraorbital proc- 

 ess is 90 mm,, and the corresponding diameter of the orbit is 60 mm. 



The flattened lachrymal bone, whose anteroexternal diameter is 

 43 mm. on the right side, is closely appressed to the anterior face of 

 the supraorbital process and is overspread by the anteroexternal angle 

 of the ascending plate of the maxillary, its narrowed inner end being 

 wedged in against the supraorbital process and the maxillary. 



The slender styliform process of the jugal that extends below the 

 orbit from the antorbital notch to the anterior face of the zj'-gomatic 

 process is missing. 



Originally, the temporal fossa seems to have been relatively short 

 (120± mm.) and high (90 ± mm.), and it is apparent that its length 



