47 



over the last premolar as is seen in Palceosyops ; the two ex- 

 ternal lobes are more erect and sharper than in any form of 

 that genus. The cingulum is complete even across the 

 internal cones, and the median valley is very deep, as in 

 Titanotherium. There is a conspicuous fold at the junction 

 of the external lobes, and a minute tubercle between the two 

 anterior lobes ; this tubercle is present only in the first 

 molar, and not throughout the series, as in Palceosyops. The 

 second molar in general form is like the first; but is larger, 

 has a deeper median valley, more conspicuous external folds, 

 and a stronger basal ridge. There is also some change in 

 the proportions of the crown ; the first measuring the same 

 in both directions, while the second is wider than it is long. 

 The last molar has but one internal cone ; the second is 

 represented by a tubercle ; which however is a true rudi- 

 mentary lobe and not a dev^elopment of the basal ridge. In 

 this tooth, the external fold is very large and the median 

 valley very deep. 



Lower Jaw. — The lower molars and premolars are very 

 much like those of Palceosyops, but are longer, narrower, and 

 higher. The incisors are not at all like Palceosyops, but are 

 compressed and laniariform, with acute crowns and sharp 

 cutting-edges. The canine is not present in our specimen ; 

 but that it was large, is shown by the long diastema between 

 the upper canine and incisors. 



Premolars. — The first is small, simple, and implanted by a 

 single fang close to the canine. The diastema between it 

 and the second premolar is about one half of that in P. major. 

 The second premolar is the most peculiar tooth in the lower 

 series ; as it carries the development of the anterior lobe at the 

 expense of the posterior lobe, to a still greater extent than in 

 Palceosyops., forming a crown like the blade of the carnivorous 

 sectorial. The third lobe of the last molar is no longer a 

 simple cone, but a functional lobe, with two crests running 

 from it, which bound a median valley. 



Teeth Measiirements. 



UPPER JAW. M. 



Length of entire dental series '275 



Length of incisor series • ■ • °375 



