INTRODUCTION. 13 
Section of Beds constituting the early tertiary (Hocene) of the Bad Lands (Mauvaises 
Terres).—(Numbered in the descending order.) 
1. Ash-colored clay, cracking in the sun, containing silicious concretions 30 feet. 
2. Compact white limestone : : , . : : : ee Ma 
3. Light-gray marly limestone . ; : - ays 
4. Light-gray indurated silicious clay (not eaaraeneas) : 3 eriBO 0 6 
5. Aggregate of small angular grains of quartz, or conglomerate, comented 
by calcareous earth (slightly effervescent) ; : ; Spy OMe 
6. Layer of quartz and chalcedony (probably gully par tial) , oak Inch. 
7. Light-gray indurated silicious clay, similar to number 4, but more ° 
calcareous, passing downwards into pale, flesh-colored, indurated, silicious, 
pee limestone (effervescent), turtle, and bone bed ‘ ‘ 3 . 25 feet. 
. White and light-gray calcareous grit (slightly effervescent) . omlo 
; Similar aggregate to number 5, but coarser. : iy Sang 
10. Light-green, indurated, argillaceous stratum @lislily Enervesreniyt 
Titanotherium bed . : d ! : : : : . : . 20 feet. 
The extensive cemetery of eocene vertebrata in the Mauvaises Terres, or Bad 
Lands, of Nebraska, was first brought to our notice in a communication entitled 
Description of a Fossil Maxillary Bone of a Paleotherium, from near White River, 
published by Hiram A. Prout, M.D., of St. Louis, in the American Journal of 
Science and Arts, for 1847, page 248. 
Nearly at the same time, Mr. J. S. Phillips, when on a visit to Chambersburg, 
Pennsylvania, observed in the possession of Dr. 8. D. Culbertson, several remark- 
able mammalian fossils, which had been sent as curiosities from the Bad Lands by 
his nephew, Mr. Alexander Culbertson, of the American Fur Company. These 
specimens, at the suggestion of the late distinguished Dr. 8. G. Morton, were 
obtained through Dr. John H. B. McClellan, a friend of Dr. Culbertson, and were 
obligingly placed in my hands for examination. A description of them was pub- 
lished in the Proceedings of the Academy of Natural Sciences, of Philadelphia, for 
1847 and 1848; and they were afterwards presented by Alexander Culbertson 
to the Academy. 
The attention of Dr. D. D. Owen having been directed to the interesting region 
whence the fossils were obtained, he requested Dr. John Evans, an assistant in 
the geological survey in which he was engaged, to pay it a visit. This gentleman 
brought home a magnificent collection of fossils, which form the basis of one of 
the chapters in the Report of Dr. Owen, before quoted.* 
Through the instrumentality of Prof. 5. F. Baird, who from the first fully appre- 
ciated the importance of a complete examination of the Mauvaises Terres and their 
animal remains, Mr. Thaddeus A. Culbertson, under the auspices of the Smith- 
* Dr. J. Leidy’s Memoir, p. 533, of the “Report of a Geolog. Surv. of Wisc., ete.” 
