Cope.J 492 [Sept. 17, 



anterior outei* cusp increases in size anteriorly, and is the large cusp of 

 the P-m. IV. It sends a branch backwards on the inner side of the crown 

 which forms the edge of the narrow concave heel. There are no cingula 

 except a short one on the anterior corners of the base of the crown of the 

 P-m. IV. Enamel obscurely wrinkled. 



Measurements. M. 



Length of posterior four molars 0180 



^. ^^ T^T- c anteroposterior 0050 



Diameters of P-m. iV <^ nnr,~ 



i transverse OOdo 



_^. ^,, T c anteroposterior 0050 



Diameters of M. I •< ^ „„„- 



i transverse OOdo 



c anteroposterior 0040 



Diameters of M. 11 ^ transverse 0032 



Diameters of M III i anteroposterior 0045 



i transverse OOdO 



Depth ramus at M. 1 0110 



Thickness " " " 0060 



Phenacodtts pitercensis, sp. nov. Three individuals. Last superior 

 molar smallest ; first and second true molars with six tubercles, two ex- 

 ternal, two median and two internal. A strong basal cingulum except on 

 inner side. Inferior true molars besides the usual five tubercles, furnished 

 with an anterior ledge with a tubercle at its interior extremity. A weak 

 external basal cingulum. A little larger than the P. vortmani. Lengtli 

 of superior true molars M. .021 ; length of base of crown of M. Ill 

 .006; do. of M. I .008; width of do. .008; length of base of crown of 

 inferior M. Ill .0085 ; width of do. in front .006 ; depth of ramus at M. 

 I .019. 



Phewacodus zuniensis, sp. nov. The least species of the genus, rep- 

 resented by the mandibles of two individuals. The first and second true 

 molars are narrowed in front, and there is no distinct anterior ledge, only 

 a minute anterior inner tubercle. The external cingulum is more distinct 

 and the enamel is wrinkled. The fourth premolar has a short base and 

 the inner cusp is much smaller than the principal one ; it has a wide heel 

 and an anterior basal tubercle. Length of true molars, M. .018 ; of last 

 true molar .006; of base of first true molar .006; width of do. .004; 

 depth of ramus at do. .011. 



Protogonia subquadrata, gen. et sp. nov. Fourth superior premolar 

 with one external and one internal lobe. True molars with two external, 

 two internal, and two intermediate lobes, both the latter connected with 

 the anterior internal by a ridge. Supposed inferior true molars with two 

 Vs with weak anterior branches ; last true molar with heel. 



This genus will enter the GhalicotheriidcB, of my system of Perissodac- 

 tyla,* if the feet are found to possess the requisite characters. It is 

 allied, apparently, also to Hyracotherium, but diff"ers in the Vs of the infe- 



*See Proceedings Amer. Philosoph. Society, 1881, p. 377-8. 



