1877.] 



225 



[Cope. 



angular, the lateral faces being longer than the posterior, and the anterior 

 angle is a narrow one. The surface of the enamel cannot be described, as 

 it is eroded at some points. The diastema is long. 



The first (homologically second) premolar is narow, and is without 

 lateral or posterior lobe or cingulum, but a third is a rudimental lobe at its 

 anterior base. The heel presents an interior tubercle, and a narrow pos- 

 tero-external lobe which embraces a medeo-external tubercle. The latter 

 becomes the external posterior tubercle on the true molars. The third pre- 

 molar is larger and wider than the second ; the niedio- external lobe be- 

 comes more external and posterior, and a median tubercle appears in front 

 of it. The posterior tubercle still sends a narrow ledge round to the outer 

 base of the medio-external lobe. The anterior lobes are more elevated 

 than the others, and are only separated by a fissure. In the fourth premolar 

 the true molar structure is seen in the regular quadri-tuberculate form. 

 There is a small tubercle in front and behind the notch of lobes, and a fold 

 descending forwards on the outer side of the external posterior lobe. In 

 the second true molar there is an additional tubercle on the middle line be- 

 tween the pairs of lobes. The median accessory tubercles are not distinct 

 on the last molar, excepting the posterior, which becomes a large heel. 

 The lobes of each pair are not deeply separated on the last two molars. 

 These teeth are rather abruptly larger than the first true molar, which is 

 little larger than the last premolar. Each of them has a narrow anterior 

 cingulum, but no other. The enamel is nearly smooth. 



Measurements . M. 

 Length of mandible from end of posterior molar to in- 

 cisive alveoli 0.190 



Length of molar series 103 



' ' true molars 062 



" diastema 054 



Width between bases of canines 020 



" of diastema 024 



" between bases of first premolars 032 



( antero-posterior 012 



Diameter of p. m. 2 j trangverse 007 



. (transverse .015 



Diameter of p. m. 4 < , . rt , ~ 



( antero-posterior 012 



_^ ( antero-posterior 021 



Diameter of m. 2 < , Mn , 



{ transverse 016 



( antero-posterior 026 



Diameter of m. 3. \ . A1[ _ 



( transverse 015 



The animal from which the above description was taken was adult. It 

 was discovered in the Loup Fork beds of North-Western Kansas by Eussell 

 Hill of this city. 



Tetralophodon campester sp. nov. 



The cranium and under jaw, with nearly complete dentition, including 

 tusks, of this species, were obtained by my assistant, Russell S, Hill. The 



PROC. AMER. PHILOS. SOC. XVII. 100. 2C. PRINTED JAN. 12, 1878. 



