82 UNDERHILL : 



India by way of land connection then existing in the north 

 between North America and Asia. At the beginning of that 

 period an upheaval occurred uniting North and South Amer- 

 ica by the Isthmus of Panama, over which wandered south- 

 ward the ancestors of our present South American llamas, 

 while by the close of the Pliocene all of the members of the 

 family in North America had become extinct. 



The Cervidce, or true deer, with their solid antlers (cervi- 

 corn) first appear in the Middle Miocene of Europe, and 

 somewhat later in the same period in North America. The 

 more specialized Hollow-horned Ruminants (cavicorn) are 

 also first found in the Miocene of Europe, represented by the 

 antelopes, and have attained their highest development in our 

 modern sheep and oxen. As to the precursors of our oxen 

 we have a very indefinite record. So far as known they first 

 appear in the Lower Pliocene of India (Siwalik Formation), 

 and before the close of that period 4:hey are found in both 

 Europe and North America. We have also in the Siwalik 

 Formation the first appearance of the bison, and remains of 

 the extinct forerunners of the North American species (yBos 

 americanus) occur in the Upper Pliocene of the United States. 

 The Bos bonasus, or European bison, a few specimens of 

 which still survive in Europe, and in the United States at the 

 New York Zoological Park, ranged over most of Europe 

 during the Pleistocene period. This species is the nearest 

 living relative of the American bison, and has been somewhat 

 confused with another species — Bos primigenius — which 

 was the wild progenitor of some of our existing breeds of 

 domestic cattle, but which is now extinct. 



The giraffe occupies a rather isolated position in the ungu- 

 late series ; while it has the paired hoofs and complex rumin- 

 ating stomach of other members of the Artiodactyla, the 

 frontal armature consists of two bony prominences covered 

 with a hairy skin which are not shed periodically, as in the 

 deer, and are never covered with a horn sheath, as in the 

 oxen. With these features and the long neck and forelegs 



