Vol. 4] Sinclair. — John Day Rodents and Ungulates. 143 



In size M. acutidens occupies a. position intermediate between 

 the John Day species M. equiceps and M. praestans. So far as 

 it is possible to compare the dental measurements with those 

 given by Marsh % for M. anceps there is close agreement, but the 

 skull of M. acutidens is not depressed between the orbits nor do 

 the molars extend further behind the orbit than in M. bairdi, as 

 is said to be true for M. anceps. 



Measurements. 



Length of cranium from premaxillae to condyles inclusive 23Smm 



Length P'-M 3 inclusive 85 



Length W-W inclusive 38.5 



Length of diastema anterior to canine 10.5 



Length of diastema posterior to canine 23 



Length of canine from margin of alveolus to tip, measured on 



lingual aspect 17.5 



M 1 , antero-posterior diameter 13 



M l , transverse diameter* 16 



M 2 , antero-posterior diameter 13 



M 2 , transverse diameter* 16.3 



M 3 , antero-posterior diameter 12.5 



M 3 , transverse diameter * 16 



University of California, 

 March, 1903. 



X Marsh. Am. Jour. Sei., 3d Ser., Vol. VII, p. 250. 



* Measured through the anterior cones at the widest part of the tooth 

 crown. 



