: 1915.] Matthew and Granger, Lower Eocene Wasatch and Wind River Faunas. BO 
~, connection that two other groups of mammals in the Clark Fork, the Limno- 
'*eyonine and the Uintatheriide, are also absent from these three horizons 
and reappear, along with Menescotherium, in the Lost Cabin. 
We have then the first appearance of the Meniscotheriide in the base 
of the Lower Eocene, or the top of the Paleocene, followed by a considerable 
period during which we get no trace of it; then, at the top of the Lower 
Eocene it suddenly appears again, in great abundance in the southern or 
New Mexican area, as a straggler in the northern district, and the family 
disappears finally, along with the rest of the Condylarthra, before the 
beginning of the Middle Eocene, or Bridger. | 
Characters of Meniscothertum: Teeth buno-lophoselenodont, m'” quad- 
rate with four principal cusps and two intermediates, the posterior one of 
which is confluent with the hypocone and forms a metaloph; the anterior 
one is crescentic and separated from both protocone and paracone by deep 
valleys. MM? triangular, without hypocone; p* like m*® but with outer 
‘styles less pronounced. Lower molars double V-shaped with high crests 
and a prominent recurved metastylid,' hypoconulids not developed; mz 
similar to anterior molars; ps like molars. Canines relatively small; inci- 
sors chisel-edged. Humerus with supracondylar foramen; carpus alter- 
nating; a free centrale; unguals long and narrow hoofs, as in Tetraclenodon. 
The composite skeleton of Meniscotherium, mounted in the American 
Museum collection, shows it to be a short stocky limbed beast with very 
large-broad and deep head. The dorsolumbar formula is placed as 14-7 
but it may have been 15-6 as in Phenacodus. The sacrum figured by Cope 
has but three vertebrae but the one used in the mount and one other in the 
collection have four coéssified vertebrae. This variation appears to be no 
more than an individual or age difference. The skeleton as mounted has 
the vertebral column too much arched in the lumbar region and the anterior 
thoracic region is placed too low, which necessitated the reduction of the 
restored scapula to unreasonable proportions. Such fragments of the 
shoulder-blade as are preserved indicate that it was not widely different. 
from that of Phenacodus primevus. | : 
Considerable Meniscotherium material has been obtained by the recent 
expeditions into the New Mexican Wasatch but there is nothing which adds 
much to our knowledge of this form. 
Three species have been described; of the two species in addition to the 
genotype, one is distinctly separable, while the other is differentiated by 
characters which seem to be of only subspecific value. 
1 Absent in mi-? of M. tapiacitis. 
