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except .in Mio lab is ( Protolabis l transmontanus (Cope) •
Proto.labia montanus is nearly identical in size with Miolabis

transmontanus but is larger than M. californicus. The advance of Protolabis
over Miolabis is shown by (a) the single-rooted condition of p!, (b) the

greater length of molars in proportion to their breadth and {c) the
hypsodonty of the dental series as opposed to brachydonty in Miolabis.

Matthew regarded Miolabis tra.nsmontanus as not well separated
from Para.tylopus (Gomphotherium) (Cope). Wortman says, "The only valid

distinction between Protolabis transmontanus and Gomphotherium cameloides
is seen in the marked reduction of the second superior premolar in the

former, and as this is in the direct line of modification leading to the
Loup Fork Procarnelus, I have thought best to regard it as of generic rank,

especially until the question of coosaification of metapodials is definitely
l 2 3
settled." The dental series P- to M- is nearly equal to that of

Paratylopus cameloides from the upper John Day in size and is somewhat
larger than that in Paratylopus sternbergi. In these forms P~ is slightly

reduced from that in the White River genus Poebr~therium. Pg in the Mint
Canyon form is considerably reduced. The diastema between I~ and C in the

John Day species is intermediate in length between Poebrotherium a.nd
Miola.bis californicus. The foregoing considerations differentiate the Mint

Canyon form from Para.tylopus.
With Miolabis transmontanus it exhibits striking affinity. In

size it is but slightly smaller. 11he premaxilla is but slightly reduced.
l
Reduction of incisors seems comparable. As mentioned previously P- is

two-rooted. Reduction of the first and second premolars is not quite so
pronounced but comparable. .1.ihe teeth are sub-hypsodont and approach the

brachydont condition found in M. transmontanus. In view of such close relation-

ship the Mint Canyon form may be assigned to the genus Miolabis.

l Wortman, J. 1., Am. Mu.s •. Bull. Vol. X, Art. VII, p. 122, 1898