O. C. Marsh on the Affinities of the Brontotheride. 85 
All the known remains of the Brontotheride are from east of 
the Rocky Mountains, in the Miocene beds of Dakota, Nebraska, 
eo discovered and explored by the writer in the summer of 
1870. 
Brontotherium ingens, sp. nov. 
A new and well marked species of Brontotheriwm is repre- 
sented in the Yale College Museum by a skull, nearly perfect, 
and other characteristic remains. The specimens preserved 
indicate that the animals to which they pertained were much 
the largest of the group, nearly or quite equalling the elephant 
in bulk, and far exceeding in size any known Perissodactyls 
living or fossil. 
are about eight inches in length, and extend upward and out- 
ward. They are triangular at the base, with the broadest face 
external. he two inner faces of each core are separated by a 
ridge, which is continued to the median line. The upper part 
of the horn-cores is rugose, and the base contains large air 
foramen is small, and ovate in outline. Just below it, there 
unusually large. There is no post-orbital process. The zygo- 
matic arches are massive, and the logs portion widely 
D 
idge. | tal con 
dyles are very large, wide apart, and extend slightly behind the 
is elongate, and its anterior face concave. € pos lenoid 
Process is very large, much extended transversely, and is longer 
ey 
* This Journal, I, vol. 1, p. 292, Sept., 1870. 
