40 Department of Vertebrate P alceoritology . 



Sumatra; and Mr. Knight's studies for this picture were 

 practically based upon that living type. 



OsBORN & WoRTMAN, Fossil Mammals of the Lower Miocene White 

 River Beds, Bull. Am. Mus. Nat. Hist., VI, 1894, p. 206, pi. iii. 



4. Protoceras, Six-horned Upper Oligocene Ruminant. 



The characters of this animal are known from complete 

 female skeletons in the American Museum of Natural History 

 and the Princeton Museum, and a very complete series of 

 male and female skulls, secured by the American Museum 

 Expeditions of 1892 and 1894. As exhibited, there is a wide 

 contrast between the male and female skulls, the latter being 

 entirely devoid of horns. The very marked recession of the 

 nasals has suggested the presence of a long, somewhat ex- 

 panded upper lip, as in the modern Saiga, while the coloring 

 of the animal is based upon that of the North American 

 Pronghorn Antelope. 



Originally reproduced by Osborn in the Century Magazine, September, 1S96. 



OsBORN & WoRTMAN, Characters of Protoceras Marsh, Bull. Am. Mus. 

 Nat. Hist., IV, 1892, pp. 351-371. 



5. Metamynodon, Aquatic Middle Oligocene Rhinoceros. 



The study is based upon the mounted skeleton. No. 546, in 

 the American Museum, and represents the general conception 

 of the animal as aquatic. The opinion as to the aquatic 

 habits of Metamynodon was very largely due to the studies 

 made for this drawing in which it became apparent that the 

 very elevated position of the orbits, the widely expanding 

 ribs, and the four complete spreading toes in the fore foot, 

 strongly suggested the general build of the Hippopotamus. 

 This aquatic life is, moreover, consistent with the presence in 

 the same beds of two other types of Rhinoceros, it being 

 improbable that the three types were all land animals. 



Originally reproduced by Osborn in the Century Magazine, September, 1S96. 



OsBORN & WoRTMAN, Pcrlssodactyls of the Lower Miocene White 

 River Beds, Bull. Am, Mus. Nat. Hist., VII, 1895, pp. 373-37$ 

 pU. X, xi. 



