
1891.] Geology and Paleontology. QII 
excluded, as being non-iron-bearing, the portion north of Sulphur 
Fork, and also the northwestern corner, in which the black waxy 
prairies of the Cretaceous are the prevailing formation. 
In this district, so restricted, there are nineteen counties, containing 
in the aggregate 14,430 square miles. In each of these counties iron 
ore exists in greater or less quantities and of varying qualities. 
The region is underlaid for the most part by strata of Cenozoic age. 
In only a few places are there exposures of Cretaceous strata, and when 
they do appear as inliers they belong to its uppermost members and 
are accompanied by salines. 
Meniscotheriidz and Chalicotherioidea.—The Meniscotheriid 
family of Condylarthra, which has been found only in the American 
Wasatch, and is represented by a single genus, has always been placed in 
a very doubtful phylogenetic position, Dr. Wortman in 1886! was in- 
clined to ‘‘regard Meniscotherium as the direct ancestor of ars 
Hyracoidea, ee their wide separation in time and space.’ 
Schlosser in the same year? recognized the striking likeness of the molars 
of Meniscotherium to those of Chalicotherium, which was at the time 
believed to be a true perissodactyl, so that he naturally did not trace 
any ancestral relationship between these forms. He considered Men- 
iscotherium (of. cit., p. 120), with Macrauchenia, to be Perissodactyla 
which had retained a very primitive foot structure. Since this paper was 
published Chalicotherium has been removed to a separate division of 
‘Mammalia, affiliated to the Perissodactyla, but representing a distinct 
line. 
I find there are many striking resemblances between the dentition of 
Meniscotherium and Chalicotherium, and it appears to me probable 
that the Wasatch genus is related to the ancestral forms of Chalico- 
therium. The resemblances consist (a) In the enlargement of the 
posterior half of the dental series, and reduction of the anterior half. 
(6) The upper molars are of precisely the same pattern ; the protocone 
is isolated; the hypocone and metaconule are united in a short 
transverse crest. (c) The similarity in the lower molars is seen espe- 
cially in the reduplication of the metaconid in both forms, and the 
absence of the third lobe upon the last lower molar. 
The differences between these genera are such as separate many 
higher from lower types, in the displacement of the foot bones and 
1“ Comparative Anatomy of the Teeth of the Vertebrata,” p. 476. 
2“ Beit. z. Kennt. Niss der Stammes-geschichte d. Hufthiere,” Morph. Jahré., Band 
I2, p. 21. = 
