CREODONTA. 275 



The third superior premolar has a base of triangular outline, the ex- 

 ternal side longer than either of the internal, which are connected by a 

 broadly rounded angle. The external cusp is of lenticular section at the 

 base, and circular section near the apex. An internal cusp is represented 

 by a strong cingulum, as in Periptychiis, which connects with the posterior 

 base of the external cusp. Tlie crown of the fourth superior premolar has 

 .a triangular base of which the anterior side is shorter than either of the 

 other two, which are subequal. The external cusp is large, simple, and 

 subconic. The internal is distinct but smaller, and is continued posteriorly 

 as a cingulum to the posterior base of the external cusp. No internal cin- 

 gulum. The crown of the first true molar is worn to the roots. The sec- 

 ond true molar is the longest of the series. Its base is a triangle, placed 

 transversely to the axis of the jaw, of which the external side is the* shortest, 

 the anterior the next longer, and the posterior the longest. The apex or 

 internal extremity of the crown is obtusely rounded. There are two sub- 

 equal external cusps, which are injured in the specimen. The internal cusp 

 is the apex of a V whose limbs form the anterior and posterior edges of the 

 grinding face of the crown, extending outwards to near the bases of the 

 external cusps. Posterior to the posterior one is a strong basal cingulum. 

 No internal, and a feint anterior cingulum. There is probably an external 

 ■cingulum, but it is broken away. The last molar is of an oval outline 

 placed transversely to the cranial axis, both the external and internal 

 extremities contracted, the latter a little more so. There is a large anterior 

 external conical cusp. The posterior external is small, and is situated at 

 ihe posterior third of the posterior border of the crown. The internal cusp 

 is well developed, and has a subcircular section. There are strong external 

 ^nd posterior cingula, and a weak anterior one, but no internal cingulum. 

 The posterior extremity of the maxillary bone within the zygoma, is imme- 

 diately above the posterior border of the last superior molar. 



Measurements of superior molars. 



M. 



Length of bases of posterior five 069 



_. . , Ti ... ( .luteioposterior 013 



Diameters base, Pm. in < ' ._„ 



( transverse WH 



Ts. , , T> • < anteroposterior 0145 



Dianaeters base, Pm. iv •; ■ ... 



( transverse Ul4 



