638 THE WASATCH AND BEIDGER FAUNiE. 



transverse diameter. The true molars are of subequal dimensions. Their 

 external cusps are subconic. All the superior molars except the first and 

 second premolars are entirely surrounded by a basal cingulum, which rises 

 into a low cusp at the anterior external angle of the crown. The third 

 inferior premolar has its two median cusps well separated, and a wide poste- 

 rior lieel. The heel of the last premolar is wider, but carries no internal 

 cusp. The external cusps on all the teeth wear into well-defined Vs. Tlie 

 posterior five inferior molai's have an external basal cingulum, but no other. 



Measurements of skull. 



u. 



Length of consecutive superior molars 0150 



Length of diastema between Pm. i and ii 0035 



Length of second premolar 0070 



Width of second premolar posteriorly 0050 



Diameters fourth premolar J ' ^ ' 



( transverse 0090 



y... , ,. , (anteroposterior '. 0085 



Diameters second true molar •; ^ 



( transverse 0112 



Length of entire premolar series - 0580 



Length of entire inferior true molar series 0'282 



T^- . /. i .. 1 (anteroposterior 0080 



Diameters nrst true molar < ' 



( transverse 0060 



Diameters last true molar ^^"^'^^P''**''"'"- ^12" 



( transverse 0065 



Depth of ramus at fourth premolar 0165 



Depth of ramus at third true molar in front 0165 



Twenty-two vertebrae are more or less perfectly preserved. Three 

 are cervicals, twelve are dorsals, and six are lumbars. The yertebrarterial 

 canal of the atlas issues at the middle of the lower side of the transverse 

 process, in a longitudinal oval fossa. The inferior face between the trans- 

 verse processes, is slightly concave on each side, and slightly convex in the 

 middle. There is a slight atlantal process. The neural spine of the axis 

 has an acute border, and is elevated behind, and extends forwards over the 

 neural canal to above the middle of the odontoid process. The atlantal 

 facets are subtriangular, and as high as wide. The anterior orifice of the 

 vertebrarterial canal issues between two ridges, which extend from the 

 upper and lower borders respectively of the atlantal facet to the transverse 

 process. Below the inferior ridge the centrum is deeply concave to a high 

 acute keel of the middle line. Between the atlantal facets this keel is ab- 

 ruptly thickened, and it becomes a low obtuse hypapophysis below the 



