i6c JEXTINCl^ 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. 



