PALMHOTHERIUM OF NEBRASKA. 551 
Upon the teeth of the latter the enamel is thinner relatively upon the external 
concave faces of the inner lobes of the upper molars, and the internal faces of the 
outer lobes of the lower molars than in O. Culbertsonii. 
ADMEASUREMENTS OF THE HEAD OF 0. GRACILIS. 
Estimated length from the summit of the inion to the incisive alveoli, : 56 
Breadth at the maxillo-malar suture below the orbits, d i ; 29 
Breadth at infra-orbitar foramina, . . 3 : : : 12 
Kstimated length of sagital crest, . f F ‘ : ; 22 
Length of upper molar series, ‘ ; : : . ; 25 
‘ lower “ cc ; : : : , ; 254 
PALAOTHERIUM. Cuvier. 
PALASOTHERIUM (?) PROUTIL Owen, Norwood, and Evans.* 
(Tab. ix., figs. 8, 3a; Tab. xii. n, figs. 3, 4, 6, 7, 8.) 
In the American Journal of Science for 1847, Dr. H. A. Prout has given a de- 
scription of a fragment of the lower jaw of an enormous Pachyderm, suspected to be 
a species of Paleotherium. The specimen was the first of the many mammalian 
remains, which have been brought to the notice of the scientific world from the 
vast Eocene cemetery of Nebraska. 
In Dr. Owen’s collection is a fragment of the left side of a lower jaw (Tab. ix., 
fig. 3a), apparently of the same animal, but of a smaller individual. It is very 
friable, and originally, i. e., after the death of the animal, was very much compressed 
and fractured from pressure. The fragment is sixteen inches long, and contains 
the true molars and portions of the fangs of the two preceding premolars. Along 
the line of the true molars, the jaw measures nine and a half inches, and below the 
last molar posteriorly is six inches in depth. 
There are also in the same collection the crown of a molar, apparently an inferior 
third premolar (Tab. xii. 8, 7), an inferior canine (8), and a fragment of an upper 
molar (6), which I suspect belonged to the same individual as the portion of lower 
aw. : 
Besides these the collection contains a left last lower molar (Tab. ix., 3), a right 
lower penultimate molar, of two other individuals of the same species, and two 
fragments of upper molars (Tab. xii. B, 3, 4), probably of the latter. The inferior 
true molars resemble those of Paleotherium in their form, but more particularly 
those of Anchitherium, in having no trace of a basal ridge internally. The crowns 
are worn upon the triturating surface into crescentic spaces, from the inner margin 
of which the sides do not shelve downwards in a convergent manner to the base of 
the teeth, as in Paleotherium; but the horns of the crescents enclose broad con- 
* Proc. Acad. Nat. Sci., v. 66. 
