SKULL OF HESPERORNIS. 7 



The palatines resemble those of the Ostrich. They are long, slender 

 bones, extending- from their union with the pterygoids, parallel with the 

 axis of the skull, and joining the premaxillaries. In one specimen, they 

 lie nearly in position, the left palatine being immediately beneath the left 

 maxillary. In front of their junction with the pterygoid, and just anterior 

 to their widest expansion, there is a deep pocket, very similar to that in the 

 palatine of the Ostrich. The anterior half of the bone is slender, and 

 tapers gradually to the extremity. 



The vomers in Hesperornis are separate, as in lizards and a few existing 

 birds. They are smaller than the palatines, and resemble the vomers of 

 JRhea, more than those of the other Hatitce. They are broadest at the base, 

 which is obliquely truncated, and they taper gradually to the pointed 

 extremity in front (Plate II, figure 8.) The thick posterior end may 

 possibly have united with the pterygoid, as well as with the palatine. 

 Both A-omers are preserved in the skull figured in Plate I, but are dis}}laced. 



The bones of the brain-case are ankylosed, but in other parts of the 

 skull the sutures are distinct, and many of them are open, as in the Ostrich 

 and other JRatitce. The orbits are large, and placed near together. There 

 i> a well-ossified interorbital septum, which is perforated by a large 

 fenestra. (Plate I, figure 1, of.) The superior temporal arch is wanting, 

 and the orbit was closed below by the strong quadrato-jugal bar. There 

 was a large temporal fossa, bounded in front by a distinct postorbital 

 process. There are well marked glandular depressions extending along 

 the roof of the orbits, as in Colymbus and some other recent aquatic birds. 



The quadrato-jugal bone is slender, and its articular head fits into a 

 deep pit in the lower end of the quadrate. There is a large triangular 

 lachrymo-nasal fossa, between the orbit and the anterior nasal opening. 

 The latter is long and narrow, and closed behind by the nasal bone. The 

 suture between the frontals and the beak was quite open. The lachiymal 

 bone is distinct, and articulates with the frontal, nasal, and maxillary. 

 The nasal is deeply excavated in front for the anterior narial aperture, and 

 below joins both the maxillary and premaxillary. 



