422 THE PUERCO EPOCH. 



tion. There are traces of anterior and posterior cingula. The base of the fourth 

 superiorpremolar is more extended transversely, to sustain the conical internal 

 cusp. The external cusp is but little longer than wide Traces of anterior and 

 posterior cingula, which are not connected with the internal lobe. The ex- 

 ternal cusps of the superior true molars are not fl.attened on the external side, 

 and have a subround section. The internal V is not very prominent inwards, 

 and is uninterrupted. The internal cusp rising from the posterior cingulum 

 is large, and is a little posterior to median in position, and its base projects 

 well inwards. The last molar is a little smaller than the others, and the 

 extern.al face is oblique. All the true molars have an external cingulum, 

 which extends into the anterior limb of the V in front, and posteriorly rises 

 to the posterior external cusp. The posterior limb of the V descends to a 

 posterior cingulum. The internal cusp descends to both anterior and pos- 

 terior cingula, of which the latter is the stronger. 



The alveolus of the inferior canine indicates a large tooth directed 

 at an angle of 45° forwards. The first premolar has a single stout root. 

 The second premolar is two-rooted, and has a subconic crown with a rudi- 

 mental heel behind. The third and fourth premolars are similar to it, dif- 

 fering in their increasing size, and the transverse extent of the small heels. 

 None of them have anterior tubercle or cingulum, as in the other species. 

 In all of them the heel of the fourth inferior premolar tooth is longer than 

 in n. rntoconns. 



The inferior true inuhus are of robust form, subequal in size, and 

 smaller than the last two premolars. They have three posterior, three an- 

 terior, and no central tubercles, and of these the median posterior and an- 

 terior are the smallest, except on the third molar, where the posterior forms 

 the robust heel. The lateral posterior are the apices of externally directed 

 angles of the summit of the crown, and are less elevated than the principal 

 anterior. These are opposite and are fused at the base. The external is 

 more elevated than the internal. The true molars all have a trace of an- 

 terior cingulum, and a trace externally between the cusps. The only in- 

 ternal cingulum surrounds the base of the anterior tubercle, on the second 

 and third true molars. The enamel of all the teeth is smooth, except a 

 faint striation on the superior premolars. 



