SYNOPSIS OF THE VEUTEBRATE FAUNA OF THE PUERCO SERIES. 327 



Externally it is bounded by a strong cingulum whose anterior and posterior extremi- 

 ties rise into strons: basal tubercles of erescentic section. The first true molar is 

 considerably smaller than the second, and has a strong postei-ior inner cingular tuber- 

 cle, l)ut no internal cino-uluni. The second true molar has the structural characters 

 of the fiist. Its external cusps are conic, and are little compressed. There is a 

 strong external cingulum, but no internal cingulum. The third true molar has a very 

 small anteroposterior diameter, and has a very strong external cingulum which in- 

 creases the transverse diameter of the croxAm. There are delicate anterior and poste- 

 rior einornla, which are continuous round the internal base of the crown. In the 

 lower molars the third is considerably smaller than the second, and its keel is but 

 little produced. The anterior part of both molars is elevated above the posterior 

 part. 



The ramus mandibuli is characterized by the rapid increase of its depth ante- 

 rior to the base of the coronoid process, and by the distance of the m. iii anterior to 

 the base of the coronoid process. The anterior border of the masseteric fossa is not 

 very strongly marked. The calcancum has the form usual in Creodonta. The sus- 

 tentaculum and internal facets are well spread apart, and the cuboid facet is triangular 

 and oblique to the long axis of the hone. 



3/easurements. ^f- 



Length of bases of posterior six superior molars 015 



true molars 021 



( anteroposterior 007 



Diameters of p. m. i < ._„ 



i transverse Uw 



Diameters of ra. 1- (transverse) 008 



( anteroposterior 0075 



Diameters of m. ii { ,.,.. 



) transverse "lOo 



( anteroposterior 005 



Diameters of m. iii { ,,._ 



^ transverse "UU 



Length of inferior m. iii 0085 



anteroposterior 009 



,.„j: 



Diametersinferiorro.il s „._ 



^ transverse OOu 



Depth of ramus at base of coronoid 020 



" front of m.ii 025 



Length of calcancum 025 



" " free calcar 014 



This species has molar teeth about the size of those of the M. protogonioides. 

 In that species also, the second superior true molar is larger than the fii'st, but the 

 third is relatively larger than in the M. (/mcflricmtcs, having two well-developed 

 external cusps. The ramus mandibuli of the M. protogoiiioides does not increase in 

 depth anteriorly, and the inferior m. iii is larger. There is nn fifth cusp on the molars. 



A. p. S. — VOL. XVT. L'P. 



