146 Wortman — Studies of Eocene Mammalia in the 



and of greater anteroposterior length than the heel ; the ante- 

 rior and internal cusps are equal in height, but the external 

 was evidently much higher ; it is somewhat damaged and does' 

 not display its full length. The principal shear is oblique, and 

 there is a posterior shear which bites against the anterior edge 

 of the first molar. The heel is relatively short, wide, and basin- 

 shaped ; the external part of the basin is the thicker and more 

 elevated. The second molar is much smaller than the first, but 

 displays practically the same structure; the trigon, however, is 

 much less elevated, and the shears are imperfect. The external 

 and internal cusps are of equal size and height, but the anterior 

 is much smaller and lower. The heel is relatively longer than 

 in the first molar, being obtusely pointed behind, where it is 

 terminated by a low but distinct cusp ; from this cusp a low 

 ridge is continued forwards and inwards to enclose the inner 



18 



Figure 18. — Right lower jaw of Viverravus gracilis MarsL ; outside view" 

 natural size. (Type.) 



Figure 19. — Superior sectorial of same; outside and iuside views; natural 

 size. (Type.) 



Figure 20. — Superior sectorial of Viverricula sp. ; natural size. 



part of the basin. Externally there is a stronger cusp situated 

 in advance and to the outer side of the last mentioned cusp, 

 which furnishes the external boundary of the basin. 



The superior sectorial displays the typical laniary structure 

 of the more highly-developed Carnassidents ; it is composed of 

 a pair of external cusps, laterally flattened and elongated in 

 such a manner as to form a pair of very effective shearing 

 blades. Of these, the anterior is the larger and more elevated, 

 being separated from the posterior by a deep vertical notch, 

 which appears as a narrow slit upon the lingual surface. At 

 the antero-external angle of the larger cusp is seen a lower, 

 but very distinct, anterior basal tubercle, internal and oppo- 

 site to the anterior edge of the main external blade is placed a 

 relatively large, pointed internal cusp of about the same pro- 

 portions of that of the Genet. In fact, the whole dentition, as 

 far as known, is strikingly like that of this living species. 



In his description of V. dawMnsia?ius, Professor Cope states 

 that the first premolar of the inferior series is a single-rooted 

 tooth. If this is true (which I am inclined to doubt), the two 





