314 THE WASATCH FAUNA. 



rior series with an internal heel; the last molar transverse; third and fourth 

 upper premolars with an anterior cone and posterior cutting-lobe; the first 

 true molar with two anterior acute cones, the posterior forming a sectorial 

 edge with the posterior lobe ; last superior molar with a single trenchant edge. 

 In the mandibular dentition, the canine teeth are directed forward 

 and upward without intervening incisors. First premolar one-rooted; 

 second and third consisting of an anterior elevated cone and posterior heel, 

 which is elevated and trenchant in the middle. The fourth premolar is 

 nearly similar, with the posterior tubercle sharp-edged. The two true mo- 

 lars with an anterior elevated portion and small, low heel; the former con- 

 sisting of three acute tubercles, of which the largest or exterior fonns with 

 the anterior a sectorial blade oblique to the axis of the mandibular bone. 

 The exterior portion of the posterior transverse superior molar is a 

 transverse blade, interior to which is one or probably two subtriangular 

 cusps. The blade shuts down in contact with the plane posterior face of 

 the united middle cusps of the last inferior molar, and the cusp shuts down 

 on the inner side of the heel of the same, where the surface is often seen to 

 be worn obliquely by it. The elevated cusps of the last inferior molar 

 close into a deep fossa of the maxillary bone; the blades of the external and 

 anterior cusps shearing against the inner side of the posterior median cusp 

 and posterior blade of the penultimate superior molar. The inner heel of 

 the latter opposes transversely the posterior heel of the penultimate inferior 

 molar, shearing somewhat with the posterior border of tlie united median 

 cusps. The external and anterior cusps of the penultimate inferior molar, 

 with their external shear, fit within the median cusp and posterior blade 

 of the antepenultimate superior molar, and are received into a correspond- 

 ing pit of the maxillary bone, which is not so deep as the postei-ior fossa. 

 The surface of the maxillary between this tooth and the last premolar is 

 only slightly concave. Thns, in this genus, and the arrangement is similar 

 in Stypolophus, each inferior tubercular-sectorial tooth makes two shears with 

 two corresponding superior molars, viz, a posterior-transverse with the 

 superior molar behind it, and an external-oblique with the superior molar 

 corresponding to it This does not occur in any i-ecent Carnivora, and is a 

 more cnm|ilex, although nuich less powerful, arrangement than they possess. 

 The skull in this genus is robust. In the O.forcipata there is an elevated 



