54 SCOTT. [Vol. V. 



and we can therefore follow the evolution of this region only 

 from the lower Miocene upward. The recent Camelidcu have a 

 peculiar type of skull, markedly different from that of the true 

 ruminants. Riitimeyer has summed up these peculiarities as 

 follows : Characteristic of the Camelina is the presence of upper 

 and lower canines and the approximation of the molar series, 

 the properly masticating surface of which is very short, to the 

 premaxillary dentition and the corresponding part of the inferior 

 dentition. The premaxillae are very complete, and reduced only 

 by small incisive foramina. Nevertheless, the skull is distin- 

 guished by the very rapid tapering of the face anteriorly, which 

 is expressed particularly in the triangular form of the palate 

 and in the very oblique position of the molar series (somewhat 

 as in the Toxodontia). The maxillary region of the skull is 

 peculiarly limited, and mainly taken up in the formation of the 

 nasal passage, having but a low alveolus and very limited mus- 

 cular surfaces. Even the jugal, as well as in the lachrymal 

 (which at least in the camel hardly appears on the face), takes 

 almost no share in the formation of the face. The infra-orbital 

 foramen lies far back, above the last premolar. There is no 

 masseter crest, and the masseter surface is almost obsolete. 

 The nasal canal is high, and roofed over by short nasals, which 

 in the llama are very broad posteriorly. The posterior nares 

 are also very high, especially in the pterygoid portion. The 

 pterygoid wings are placed vertically ; and in the llama, as in 

 young animals, are perforated by unusually large sphen-orbital 

 foramina. Characteristic in the cranium is the small extent of 

 the frontal zone as compared with the parietal zone, in the for- 

 mation of which the very high squamosals take a large share. 

 The orbits are very prominent, in spite of which the external 

 openings of the supra-orbital canal are in the camel almost 

 median in position, less so in the llama. A further consequence 

 of these relations is the displacement of the orbits into the facial 

 region above the molar alveoli, and the extraordinary length of 

 the temporal fossa, at least in the camel. Of the occipital 

 bones, only the supra-occipital extends upon the roof of the cra- 

 nium, and in the camel is raised into a great crest. The paroc- 

 cipital processes are in both forms reduced to a minimum ; the 

 auditory bullae are much inflated in the llama, in the camel they 

 are strongly compressed, and with a very deep styloid groove. 



