860 THE JOHN DAY FAUNA. 



boundary of the masseteric fossa is well mai'ked, and terminates below the 

 anterior border of the first molar. The grinding face of the molars is verj' 

 oblique anteroposteriorly, and that of the first molar is rather smaller than 

 that of the second and third. It has no anterior expansion at the alveolus. 

 The tuberosity of the incisive alveolus is not very prominent. 



Measurements. 

 No. 1. 



M. 



Length of skull from end of uasal bones to occipital condyles, inclusive 046 



Length from front of premaxillary bone to base of Pm. iv Oiil 



Length of molar series on base 009 



Length from occipital condyles to junction of otic bullae, inclusive Oil 



Length of nasal bones , 020 



Length of supraoccipital bone 008 



Width of otic bulla at middle 006 



Length uf tympanic tube 005 



Width of muzzle at middle 009 



Width of interorbital space C07 



Width of slcull at anterior extremity of glenoid cavity 0165 



Width of skull at meatus 0205 



Width of occipital hone posteriorly 013 



Widtli of foramen magnum OOfi 



Leugtii of inferior molars on alveoli 0080 



Elevation of tirst molar above alveolus 0036 



Width of crown of second molar .0025 



Depth of ramus at third molar 0070 



Width of ramus below at third molar 0050 



No. 2. 



Width of interorbital space 007 



Width of muzzle at middle 0086 



Elevation of skull from second molar Ol:JO 



Length of inferior molar series 0072 



Depth of ramus at M. 2 0072 



Widtli of inferior face at M. 2 0043 



Width of inferior incisor 0018 



Distance between infraorbilal foramen and M. 1 0050 



Besides the characters already mentioned, the somewhat greater inter- 

 orbital width distinguishes this rodent from the E. cavifrons. 



Entoptychus lambdoideus Cope. 



Bulletin U. S. Geol. Survey Terrs., IV, 330. 

 Plate LXIV; fig. 2. 



This species is represented by two parts of crania, which include the 

 interorbital and adjacent regions, with the molar teeth. A nearly entire 

 skull presents some of the characters of this species and some of those of 



