MESODONTA. 229 



is rounded, the posterior cusp having consequently a more interior posi- 

 tion. Between each pair of external lobes a small tubercle rises from the 

 cingulum, as in most ungulates with external crescents. The anterior inter- 

 nal tubercle is connected with the anterior basal cingulum by an oblique 

 ridge. The posterior inner tubercle is independent, and between it and 

 the posterior external cusp is a low, angular tubercle. Like the posterior 

 inner tubercle, this one is wanting from the fourth premolar. A loose 

 canine from the same specimen has a sharp edge on the posterior border of 

 the crown, which is terminated at the base by a small, acute tubercle. A 

 longitudinal concavity bounds one side of the edge. The infraorbital fora- 

 men opens above the posterior root of the third premolar. 



On the inferior molars of the same specimen, the second cusp of the 

 anterior inner pair is rudimental on the last tooth, and distinct on the penulti- 

 mate. The heel of the last molar is large, and its internal border is crenate, 

 and the posterior border is notched. The three other lobes are robust. The 

 lateral angles of the heel of the penultimate molar are prominent. No 

 cingula on inner bases, traces only externally; enamel smooth. 



The last two pi-emolars are preserved in the rami of another specimen. 

 Both are rather robust and have wide heels; that of the third very short. 

 The latter has no anterior basal lobe; in the fourth it is a rudiment on the 

 anterior cutting-edge. The latter has an internal tubercle; the third has none. 



Measurements. 



No. 1. 



M. 



Length of superior molar series 0280 



Length of superior premolars 0150 



Length from second (first) incisor to maxillo-premaxillary suture 0060 



„. , , „ , , (anteroposterior 0048 



Diameters of fourth premolar/ , „^„ 



' J transverse 0070 



„. . . ,, , (anteroposterior 0060 



Diameters of second true molar ? . „.„„ 



( transverse 0080 



„. , „ , , , , (anteroposterior 0050 



Diameters of last true molar { . ^„ 



I transverse 0065 



No. 2. 



Length of bases of Pm. Ill, IV 0095 



I anteroposterior 0050 



Diameters of Pm. IV< transverse '. 0040 



( vertical 0038 



From collections made by Jacob L. Wortman. 



