412 THE PUEKCO EPOCH. 



are larger. The true molars have the crown contracted upwards from the 

 base. The cusps are rather elevated, the anterior the most so. The ante- 

 rior median is nearly as high as the anterior inner, and like it, is connected 

 with the anterior external by a thin ridge, the two forming a V. The pos- 

 terior cusps are connected by a continuous edge, in which the posterior 

 median is barely distinguishable. On the last molar, however, it forms a 

 large and prominent fifth lobe. The cingula are very rudimental. Enamel 

 smooth. 



In the second specimen the crown of the fourth premolar was exposed 

 after removing the temporary molar from above it. The internal crest is 

 like that of the corresponding tooth in the A. seetorius, continuing into a 

 wide cingular ledge at the anterior base of the external cusp. The supe- 

 rior true molars of this specimen have the general form of those of the 

 type, and differ from those of the A. seetorius. They liave, however, a 

 stronger external cinffulum than those of the latter. This character is seen 

 to be still more marked in the third cranial specimen, where the cingulum 

 is more produced at the interior and posterior angles of the crown. In the 

 specimen the external faces of the external cusps are quite flat, and on the 

 second true molar their apices are inclined inwards. Specimen No. 2 is 

 intermediate between 1 and 3 in this respect. It is quite possible that Nos. 

 2 and 3 belong to a species distinct from No. 1, and if this is the case they 

 must be regarded as the types of Anisonelms gillianus, as the first descrip- 

 tion of the species was first principally drawn from them. The inferior 

 first true molar of No. 2 differs from that of No. 1 in the smaller size of the 

 anterior inner and anterior median cusps, and in the larger size of the pos- 

 terior median. Another inferior molar i.s intermediate between the two. 



The temporary fourth premolar of both jaws is preserved in No. 2, 

 and of the superior series in No. 3. That of the superior series resembles 

 a true molar more than it does its successor. In fact, it is identical with 

 the true molars, excepting in the smaller size of the internal cusp, which is 

 only a little posterior. The external cusps differ from eacli other ; the 

 anterior is erect ; the inner is a little inclined inwards, forming a V. Its 

 appearance reminds one of the permanent first true molar in Coryphodon. 

 The last inferior milk molar only differs from a true molar in the smaller 



