160 EXTINCT MONSTERS. 
Dinocerata had been found, offered so inviting a field that, in the 
spring of 1871, Professor Marsh began to explore it systematically. 
He organised an expedition, with an escort of U.S. soldiers, 
and the work continued during the whole season. In this way 
a large collection was secured. Explorations were continued 
in the spring of the following year, which resulted in the dis- 
covery of the type specimen of the Dinoceras mirabile. Another 
expedition was organised in 1873, also with an escort of soldiers, 
and a great many specimens were collected. ‘These researches 
were continued during 1874, and again in 1875, with good 
results. Since then various small parties have been equipped 
and sent out by Professor Marsh to collect in the same region of 
the “ Bad Lands ;” and, finally, during the entire season of 1882, | 
the work was vigorously prosecuted under his direction, and 
afterwards under the auspices of the United States Geological 
Survey. This brief account of the difficulties and hardships 
encountered by Professor Marsh and his companions, for which we 
are indebted to his exhaustive monograph, will serve to give some 
idea of the nature of those labours, undertaken in the cause of 
Science, which he has brought to so successful an issue. 
In the country east of the Rocky Mountains, including the 
states of Dakota, Nebraska, Wyoming, and part of Colorado, 
Professor Marsh has discovered the remains of yet another strange 
group of large quadrupeds. The best known of these is Bron- 
tops, of which the skeleton is seen in Fig. 45. These animals 
lived after the Dinocerata, namely, in the Miocene period, and were 
the largest American mammals of that period. ‘They constitute a 
distinct family more nearly allied to the rhinoceros than to any 
other living form. The skeleton on which Fig. 45 is founded was 
the most complete of any yet discovered by Professor Marsh. 
Portions of it were exhumed at different times, but it was first 
found in 1874. Our artist has made the restoration seen in 
Plate XV. from this skeleton, as figured by Professor Marsh. 
