440 THE WASATCn EPOCH. 



laterals, and is in contact with their bases. In some specimens the interior 

 extremity of the anterior ledge develops a low tubercle, and in most a sim- 

 ilar low tubercle is found on the posterior edge of the anterior inner cusp. 

 On specimens where these tubercles are unusually distinct, I proposed the 

 species Phenacodus trilobatus. Present information does not substantiate its 

 distinctness. The enamel of the inferior molars has a very obsolete ru- 

 gosity. In the description of this species in the Vol. IV Wheeler U. S. 

 Geological Survey, p. 175 and Plate XLV, fig. 2, I was guilty of a trans- 

 position of some of the separate superior molars, on which it was based. 

 Thus the tooth regarded as first superior molar is really the last, and the 

 teeth should form a series from the left to the right, instead of from the 



right to the left. 



Measurements of slull and teeth. 



Length of crauium from apex of premaxillary to superior border of foramen magnum inclusive 



(measured below) 237 



Length from apex of preinaxillary to vertical line from free end of nasal bone 068 



Length from premaxillar.v to anterior edge of orbit 115 



Length from preniaxillary to palatal notch • ^'-^ 



Length from premaxillary to post glenoid process li^l 



Lone diameter of meatus auditorius esternus 0095- 



Width of palate between canines ^'~' 



Width of palate between last molars 03-2 



Width between postglenoid processes 050 



Width between carotid grooves "^^O 



Width of occiput at foramen magnum 062 



Width at anterior parietal region (least) 0:57 



Width of interorbital region 0<0 



Greatest width of anteiior nares 039 



Depth at front of orbit ^'^ 



Length of premaxillary to front of canine (axial) Oas 



Long diameter of canine alveolus 010 



Length of premolar series 048 



Length of base of second premolar Oil 



Diameters third premolar < "" '"'^"^ ^ niA 



( transverse "-'lo 



Diameters fourth premolar^ ""'«™P°«'*'"""" °!'^ 



( transverse ^'l* 



Diameters second true molar ^""♦""P"*''"'"'" ^J? 



( transverse "'o 



r,. . .1 • 1 » 1 < anteroposterior Oil 



Diameters third true molar •; ' „,., 



( transverse ^'i-* 



Length mandibular ramus l'^-' 



Length symphysis (in oblique axis) 048 



Elevation of condyle of mandible 071 



Elevation of coronoid process 096 



Depth at posterior border of symphysis 028 



