MESODONTA. 211 



No. 2. 



M. 



liengthof five superior molars preserved 0410 



Length of premolar series 0325 



Length of bases of Pm. I and II 0125 



„. . „ „ -., ( antero-posterior 0097 



Diameters of Pm. Ill < ^ ' 



< transverse 0098 



T.. . 1. J. i , , c antero-posterior 0086 



Diameters of first true molar K „.„,. 



J transverse 0133 



Antero-posterior width of base of crown of canine 0080 



Transverse width of base of crown of canine 0050 



Wind River Basin, Wyoming. J. L. Wortman. 

 EsTnoNYX sPATULARius Cope. 



American Naturalist, 1880 (Nov. 25), p. 908. 

 Plate xxiv a, figs. 22-25. 



Represented by five molar and premolar and two incisor or canine 

 teeth, apparently belonging to one individual. These are about the size of 

 those of E. bisulcatus, but present several differences of detail. Thus the 

 basin of the heel of the last inferior molar is not obliquely cut off by a 

 crest which extends forwards fi-om the heel, but is surrounded by an ele- 

 vated border, which rises into a cusp on the external side. The incisor- 

 canine teeth are more robust than those of E. bisulcatus, one of them espe- 

 cially having a spoon-shaped crown, with the concave side divided by a 

 longitudinal rib, on which the enamel is very thin. The enamel descends 

 much further down on the external than the internal side of these teeth. 

 The rodent-like tooth does not accompany the specimen. Length of base 

 of last inferior molar, .009; width anteriorly, .005; length of crown of 

 canine incisor No. 1, .009; width at base, .005; length of crown of second 

 canine incisor at base, .012 ; width, .006. 



Basin of the Big Horn River, Wyoming. J. L. Wortman. 



MESODONTA. 



Since 1872 the Eocene formations of the Rocky Mountains have been 

 known to contain the remains of numerous species of Mammals which pos- 

 sess greater or less proportions of characteristics of the order Quadrumana. 

 Some of these were referred by their first describers to the Insecfivora, and 

 others to the Ungulata. In October, 1872, the writer described a genus, 



