257 



The molars show no characteristic differences from those of the llama and 

 camel. The narrow fold seen projecting outwardly in advance of the antero- 

 external lobe of the last molar, and in a less degree in the second molar, in 

 the llama, is nearly obsolete in the fossil. 



The premolar presents some difference from the corresponding tooth in 

 the llama. The crown is thickest, and is rounded behind, and it narrows 

 forward to the anterior subacute. border, which is convex longitudinally, and 

 is thickened toward the bottom. The outer side is not impressed at the back 

 part, as in the llama, and is feebly impressed at the fore and upper part. The 

 inner side also is but moderately impressed along the middle, compared with 

 its condition in the llama. A deep enameled pit occupies the inner back part 

 of the crown, penetrating from the triturating surface, as in the latter. The 

 pit opens backward for a considerable portion of its depth, and is closed in 

 this position by apposition with the succeeding tooth. 



The measurements of the teeth, in comparison with those of the camel 

 and llama, are as follows : 



Fourth premolar: 



* Breadth of crown where greatest 



* Width of crown where greatest. . 

 Length of crown to origin of fangs. 



First molar : 

 Breadth of triturating surface. 

 Width of triturating surface . . 

 Length of crown 



Second molar: 

 Breadth of triturating surface.. 

 Width of triturating surface . . . 

 Width of crown where greatest. 

 Length of crown 



Third molar : 

 Breadth of crown where greatest: 

 Width of crown where greatest . . . 

 Length of crown . „ 



Auchetiia 

 hesterna. 



Lines. 



13 



G 



20 



20 



10£ 



20~ 



2G 



10 

 30 



31 

 10 

 •11 



Auchonia 

 lama. 



Lines. 



3 

 G 



9 

 5f 



13 



7 



Camel. 



Lines. 



12 



7 

 14 



18 

 9 



23 

 10 

 10 

 1G 



28 



10 

 17 



* For brevity I Lave used breadth for the antero-posterior diameter, and width for I he transverse 

 diameter. 



33 a 



