Chapter M

Length of entire molar series (about) ·080
Length of premolar series ·033
Length of true molar series (about) ·047
Fore-and-aft diameter of fang of canine ·008
Distance between canine alveoli ·009
Length of diastema ·115
Length of the first molar ·015
Breadth of the first molar ·010
Depth of ramus below last molar ·0245
Depth of ramus below last premolar ·0215
Greatest thickness of ramus ·017
Length of symphysis (about) ·030

Found at Henry's Fork.

Hyrachyus -------- ?

There are three premolars of the upper jaw which we cannot refer to any known species; but they are too imperfect to justify the formation of a new species for their reception.

What appears to be a first premolar is inserted by a single broad fang; it is too much worn to show the characteristic enamel folding, and is peculiarly broad and short. The second premolar shows the usual foldings of _Hyrachyus_; save that a distinct valley enters the tooth from the posterior edge, running forward to the transverse crest, and inclosed by the curving backwards of the internal cone. The crown is nearly square; the basal ridge is scarcely marked at all.

_Measurements._