Bibliography. 297 
fossils, of unusual beauty, (seven of which are devoted to the remarka- 
ble mammalia from the Eocene tertiary of Nebraska,) besides various 
Views, sections and maps. We might interest our readers with ex- 
tended citations from its pages, but can add in this place only the fol- 
lowing extracts relating to 
general features and ancient Mammalia of the Mauvaises Terres 
of Nebraska. 
“After leaving the locality on Sage creek, [a southern branch of the 
stitute a world of its own, and which appears to have been formed, 
partly by an extensive vertical fault, partly by the long-continued influ- 
ence of t scooping action of denudation. 
The width of this valley may be about thirty miles, and its whole 
length about ninety, as it stretches away westwardly, towards the base 
the gloomy and dark range of mountains known as the Black Hills. 
lis most depressed portion, three hundred feet below the general level 
of the surrounding country, is clothed with scanty grasses, covert 
® soil similar to that of the higher ground. 
To the Surrounding country, however, the Mauvaises Terres present 
the most striking contrast. From the uniform, monotonous, open prai- 
Tie, the traveller suddenly descends one or two hundred feet, into a val- 
ley that looks as if it had sunk away from the surrounding world ; 
leaving Standing, all over it, thousands of abrupt, irregular, prismatic, 
and columnar masses, frequently capped with irregular pyramids, and 
Stretching up to a height of from one to two hundred feet, or more, — 
So thickly are these natural towers studded over the surface of this 
*xltaordinary region, that the traveller threads his way through deep, 
confined, abyrinthine passages, not unlike the narrow, irregular streets 
and lanes of some quaint old town of the European continent. Viewed 
In the distance, indeed, these rocky piles, in their endless succession, 
8ssume the appearance of massive artificial structures, decked out with 
all the accessories of buttress and turret, arched doorway and clus-— 
wred shaft, pinnacle, and finial, and tapering spire. One might almost 
imagine oneself approaching some magnificent city of the dead, where 
the labor and the genius of forgotten nations had left behind them a 
(ude of monuments of art and skill. 
the realities of the scene soon dissipate the delusions of the distance. 
The castellated forms which fancy had conjured up have vanished; and 
ound, on every side, is bleak and barren desolation. : 
Then, too, if the exploration be made in midsummer, the scorching 
