210 Wortman — -Studies of Eocene Mammalia in the 



normal in their relations to the crown, the anterior one being 

 distinct in all the molars. The heel of the first and second 

 molars has the usnal two cusps and is but little wider than the 

 anterior portion or trigon. In the last molar, however, the 

 heel has four cusps, which is again a unique character among 



143 



Figure 143. — Left lower jaw of Washakius insignis Leidy ; inside and 

 crown views ; two and one-half times natural size ; drawn from two speci- 

 mens. 



Figure 144. — Last left lower molar of Washakius insignis Leidy ; crown 

 view ; five times natural size. 



the Primates. An outline view of the grinding surface of the 

 crown o£ the last lower molar of the left side, enlarged live 

 times, is given in figure 144, which represents accurately the 

 arrangement of the cusps. The enamel of the crowns of all 



145 



146 



„__ iitt) 



Figure 145. — Last two superior molars of the right side of Washakius 

 insignis Leidy ; crown view ; four times natural size. 



The postero-internal cusp of the second molar is not represented strong 

 enough in the drawing. 



Figure 146. — Left superior maxillary of Washakius insignis Leidy ; crown 

 view ; two and one-half times natural size. 



the lower teeth is strongly wrinkled, that occupying the valley 

 of the heel especially so. 



The fragment of upper jaw associated with the lower teeth, 

 figure 145, contains the second and third molars. The second 

 molar is larger than the third, although the disparity in size is 

 not so great as in Omomys or Hemiacodon. The crowns are 



