30 



LOWER JAW. 



Incisor series 



Median incisor fang, length 



Median incisor crown, length 



Diameter of median incisor crown, transverse 



Diameter of lateral incisor crown, transverse 



Diameter of lateral incisor crown, anteroposterior 



Length of fang of canine 



Extreme breadth of fang of canine 



Crown of canine, length. 



Crown of canine, fore-and-aft diameter at base. . . . 



Diameter of first premolar, antero-posterior 



Diameter of first premolar, transverse 



Diastema between first and second premolars 



Length of entire molar series 



Length of molar series, omitting first premo ar 



Diameter of last molar, antero-posterior 



Diameter of last molar, transverse 



Depth of jaw below last molar 



Among other specimens obtained at the divide between 

 Henry's Fork and Cottonwood Creek, was a nearly complete 

 but somewhat shattered skeleton of a Palceosyops major, 

 found contiguous to the head of the same, parts of which are 

 just described. Portions of these are figured on a one fourth 

 scale in Plate II. The description is from a nearl)' perfect 

 atlas and axis, several cervical, dorsal, and lumbar verte- 

 bras, more or less complete, and a portion of the sacrum and 

 pelvis, in addition to several bones of the limbs. 



The atlas has a broad inferior arch, contracted antero- 

 posteriorly, and deeply notched for the prominent odontoid 

 of the axis. The heavy superior arch, inclosing a large and 

 depressed neural canal, is capped by a low tuberosity. It 

 slopes into a flat, and very broad transverse process, which 

 thickens backwards, and is perforated by the vertebraterial 

 canal. Forwards the transverse process is notched for the 

 exit of the first spinal nerve. The anterior or condylar faces 

 are continuous, deeply concave from above downwards ; and 

 slightly so from side to side ; while the posterior faces are 

 oval, nearly flat, and directed backwards and inwards. 



The axis is proportionately small, with a long opisthocoe- 



