622 THE EOCENE FAUNA. 



M. 



Length of inferior dental series from I. i to M. iii, inclusive 0920 



Length of inferior molar series 0780 



T-,- i v • r • • (anteroposterior 0075 



Diameters base inferior canine < '^ „„^. 



C transverse OUoO 



Length last three premolars 0265 



Length base Pm. ii 0090 



Length base Pm. iii .0087 



Length inferior true molar series 0320 



^. , ,, ..(anteroposterior 0106 



Diameters M. ii .' ' „„_„ 



( transverse 0U7b 



T^. . ,, ...(anteroposterior 0153 



Diameters M. 111.? ' 



j(ai 

 < tr 



transverse 0076 



Length of symphysis (olilique) 0360 



Depth of ramus at diastema .0200 



Depth of ramus at Pm. iii 0230 



Depth of ramus at M. ii 0280 



Vertical diameter of orbit (?distorted) .. 0285 



Jaws and teeth of more than twenty inciividuals of this species were 

 brought from the Wa.satch beds of the Big Horn River by Mr. J. L. Wort- 

 man. They vary somewhat in size, some being a Httle smaller than the 

 individual above described. The latter was as large as a fully grown sheep. 



Systemodon semihians Cope. 



Paljeontological Bulletin No. 34, p. 184, Feb. 20, 1882. 

 Plate LVI; figs. 3-4. 



This species was also abundant in the Big-Horn region, jaws and teeth 

 of sixteen individuals having been obtained. Its dimensions are a little 

 smaller than those of the S. tapirinus, especially as to the premolar teeth. 

 There is also a short postcanine diastema, which is not seen in the S. ta- 

 pirinus. 



The proportions of the maxillary series are represented by a left max- 

 illaiy and premaxillary bone, with all the teeth in place, but the crowns 

 lost from the first premolar anteriorly. The crowns of the true molars are 

 somewhat worn, so I confine the description of these to the premolars. 

 The third and fourth have considerable transverse extent, the latter being 

 wider than long. The second has scarcely any internal tubercle, but only 

 a low postero-internal heel. The internal tubercle of this tooth is large in 

 S. tapirinus. The crown has two cusps, the posterior lower. The last two 

 premolars have two external cusps close together. The}' have also an ante- 

 rior external cingular lobe, as in the true molars. There is a posterior 



