xi.] AKTIODACTYLA. 197 



remarkable for the conformation of the upper part of the 

 face. The anterior nares extend backwards almost to a 

 level with the front edge of the orbits, and have an unusual 

 vertical expansion. The nasal bones are aborted or coa- 

 lesced with the frontals. The turbinals are very short. 

 The lacrymals enter largely into the side walls of the 

 anterior nares. The ascending processes of the premaxillse 

 are small, and very widely separated from the nasals. In 

 the living animal the edges of these greatly expanded narial 

 apertures are continued forwards into a truncated, almost 

 proboscidifonn muzzle without any bony support, giving the 

 contour of the face a totally different appearance from that 

 presented by the skull. 



In the Elk (Alces), and a small Abyssinian Antelope 

 (Neotragus saltiand), the nasal bones are very much shorter 

 than they are in ordinary ruminants. 



The Tylopoda (Camels and Llamas) and the Tragulina 

 differ from most of the Pecora^ and resemble the non-rumi- 

 nating Artiodactyles in having the tympanic bulla filled with 

 cancellated bony tissue. 



The skull of the Pig shows in section that the axis of the 

 face is bent down upon the basicranial axis almost as much 

 as in the Sheep, a disposition which increases with age. 

 Though the form of the cranial cavity is not very different 

 from that of the Sheep, the external appearance of the 

 hinder-part of the skull is greatly changed by the elevated 

 and backward sloping occipital crest, formed by the union 

 of the supraoccipital (concave from side to side posteriorly) 

 and the parietals. The latter have their outer and inner 

 surfaces widely separated in the adult Pig by large air-cells. 



The frontal is broad and flat between the orbits, and 

 sends out a small postorbital process, which does not join the 



