Case L. 



22 GUIDE TU THE FOSSIL MAMMALS AND BIRDS. 



Pier-case 8. on the bune ^vllel•e the horn would be attached. The 

 earliest rliinocerose.s are the smallest and have the front 

 teeth best developed. Some of them (R//racodon), as 

 proved by the shape of the back of the skull, could only 

 use their jaws for crushing or cho])ping their food, and had 

 not acquired the powerful grinding bite characteristic of 

 their modern rei)resentatives. Illustrations are exhibited in 

 Pier-case 8 and Table-case 4. 



Pier-ease 6. A very peculiar rhinoceros, Elasmotherium sihiricani, 

 with a skull more than a yard in length, lived in Siberia and 

 part of south European Eussia in the Pleistocene period. It 

 must have Ijorne an enormous horn, not on the nose, but on 

 a bony prominence in the middle of the forehead above the 

 eyes. Its teeth, though formed on the rhinoceros-plan, are 

 shaped like those of a horse. They have crimped enamel 

 and must have been very eflective giinders for a long-lived 

 animal. Plaster casts of the skull and other remains are 

 exhibited in Pier-case 6. 



Pier-case 8. The Titanotherildae, of the Eocene and Oligocene periods 

 in America, seem U) have been closely related to the early 

 rhinoceroses. Some typical remains of the latest genus, 

 TifanotJicrivm itself, are placed in Pier-case 8, and a fine 

 skull is exhiljited in a special Case (marked L). The head is 

 shaped like that of a rhinoceros ; Ijut the roof of the nose- 

 cavity bears a pair of small bony horns or horn-cores, and 

 the teeth form an almost or quite continuous series in the 

 mouth. The fore foot has four toes, of which the two middle 

 ones are less unequal tlian in the tapirs ; the hind foot has 

 three toes. Some species attained a very large size, 15 to 

 18 feet in length (Eig. 12). 

 Pier-case The typical one-toed horses (of family Equidse), which 



are only found in a wild state at the present tlay in Africa 

 and Asia, ranged also over Europe and the whole of North 

 and South America during the Pleistocene period. Some of 

 them, whose bones cannot be distinguished from those of 

 Eqiius cahaUus, wandered even into the Arctic Pegions. 

 Most of them l)elonged to the genus Equiis, but a few in 

 South America were peculiar, notably the Hijipidium and 

 Onoliippidunn found in the Argentine Eepublic. As shown 

 by a plaster cast of the skull in Pier-case 10, the latter genus 

 was characterised by a remarkable development of the nose : 

 it is also known to have possessed unusually short and stout 

 legs. All the American horses seem to have Ijecome extinct 

 before the New Woild was colonised from Europe in historic 



10. 



