FREE INSTITUTE OF SCIENCE 

 UINTA SELENODONTS 



IO3 



MEASUREMENTS. 



Upper dentition, length C to M-3 . 0.0S1 

 " canine, ant. -post. diam. . . .0075 

 " " transverse diameter. .007 



" premolar series, length . . .030 



P-i, length 0085 



" P-2, " 009 



" P-2, width 0045 



" P-3, length 009 



P-3, width 0085 



Upper P-4, length 0.007 



P-4, width on 



" molar series, length . . . .035 



" M-l, length 010 



" M-l, width oil 



" M-2, length OI 35 



" M-2, width 0155 



M-3, length 014 



" M-3, width 0165 



Of the skull very little is preserved, only the upper jaws and the occiput, 

 but from these may be learned facts of some significance. It may be pre- 

 sumed that the cranium was even longer and the face shorter proportionately 

 than in Agrioclurrus, for not only is this the general rule in comparing earlier 

 and later members of the same phylum, but in Protagriocluvrus the extremely 

 short diastema behind the upper canine points to the same conclusion. Prob- 

 ably the proportions of the cranial and facial regions were very much as in 

 Protorcodon. The occiput resembles that of the latter genus and also that of 

 Agriochccrus, being broad ventrally and narrowing much towards the dorsal 

 side. The basioccipital is wide but tapers anteriorly, and is only moderately 

 convex, without median keel. The condyles are large and very prominent, 

 and in shape and proportions almost exactly resemble those of Agriochcenis. 

 The exoccipitals are broad and form a wide convexity above the foramen 

 magnum, on the dorsal margin of which they give off two processes, with a 

 deep cleft between them. The paroccipital process is long and is curved 

 backward ; its anterior face is concave, as though it had partly embraced a 

 small tympanic bulla; the process stands well in front of the condyle, and 

 between the two is a large and deep fossa. Another fossa lies upon the side 

 of the exoccipital, between the condyle and the crest of the inion. The 

 supraoccipital is concave and its crest is on each side extended into the wing- 

 like processes which occur in this genus, as in almost all the oreodonts and 

 agriochcerids. Both the occipital and sagittal crests are very prominent, and 

 the latter is quite thick and heavy. Only a narrow strip of the mastoid is 

 exposed upon the surface of the skull, and there is no distinct mastoid process. 

 The tympanies are not preserved, but it is clear from the shape of the basi- 

 occipital that they cannot have been so largely inflated as in Agriochcerus. 



The jugal is relatively stout, especially in the vertical dimension; trans- 



