340 Bulletin American Museum of Natural History. [Vol. XXXIV, 
Phenacodus primevus robustus subsp. nov. 
Type, No. 15275, a left ramus with p3-m3 in unworn condition; Gray 
Bull beds, Bighorn basin, Wyo., Exp. 1910. 
Six specimens of P. primevus from the Gray Bull have teeth of about 
the same anteroposterior dimensions as the plesiotype but with greater 
transverse diameters, giving the teeth a much more robust appearance. 
One specimen (No. 15266) shows upper molars and fourth premolar 
(Fig. 3). Another (No. 4370) has upper and lower jaws, femur, tibia, 
and lower end of scapula. The limb bones, while not much longer than 
those of the skeleton of P. primevus, are much more massive, the compara- 
tive widths across the femoral condyles being 58 and 66mm. They indicate 
an animal perhaps two or three inches taller and of at least twice the weight. 
Phenacodus intermedius sp. nov. 
Type, No. 15761, upper and lower jaws; Gray Bull beds, Five Mile 
Creek, Bighorn basin, Wyo. Exp. 1911. 
About twenty-five specimens from the Gray Bull beds represent a form 
somewhat smaller than the type of P. hemiconus from the same beds and 
locality. This group seems too small to include in the species P. primevus. 
Comparing the type with the type and topotype of P. hemiconus,which 
form approaches it most nearly in size, there is a greater reduction of the 
m? and a relatively larger p* than in P. hemeconus. ‘The intermediate cusps 
of the molars are also less distinct; on m? the metaconule is entirely absent. 
In p3 the metaconid is placed lower than in P. hemiconus. 
Paratype, No. 15777, a maxilla supporting all teeth from canine to m3, 
unworn; Gray Bull beds, Shoshone River, Bighorn basin, Wyo. Exp. 1911. 
This beautifully preserved specimen (Fig. 9) affords a good supple- 
mentary type, since it presents three anterior teeth not preserved in the 
holotype. The posterior half of the third molar is missing, but otherwise 
the teeth are perfect. The specimen agrees very closely with the type, 
except that the metaconule is absent from m! instead of m?. The canine 
is large, relatively about the same size as in P. primevus; p' is shaped like 
the canine and half the size, p? shows a broad outer cusp and posterior 
internal ledge. There is just a suggestion of two or three cusps on the 
_ posterior ridge of the protocone. P®* presents 5 cusps in line on the outer 
face; the large protocone, a lower cusp, the tritocone, posterior to the pro- 
tocone, and a still lower accessory cusp posterior to the tritocone, while at 
