41 



and is erroneous. These primitive Deer do not have the orbit 

 closed behind, and they have all the four metapodial bones 

 entire, although the second and fifth are very slender. In the 

 upper Pliocene, a true Cervus of large size has been discovered. 

 In the Post-Tertiary, Cervus, Alces, and Tarandus have been met 

 with, the latter far south of its present range. In the caves of 

 South America, remains of Cervus have been found, and also two 

 species of Antelopes, one referred to a new genus, Leptotherium. 



The Hollow-horned Ruminants, in this country, appear to 

 date back no further than to the lower Pliocene, and here only 

 two species of Bison have as yet been discovered. In the Post- 

 Tertiary this genus was represented by numerous individuals 

 and several species, some of large size. The Musk Ox (Ovibos) 

 was not uncommon during some parts of this epoch, and 

 its remains are widely distributed. 



No authentic fossil remains of true Sheep, Goats, or Giraffes 

 have as yet been found on this continent. 



The Proboscideans, which are now separated from the typi- 

 cal Ungulates as a distinct order, make their first appearance in 

 North America in the lower Pliocene, where several species of 

 Mastodon have been found. This genus occurs, also, in the 

 upper Pliocene, and in the Post-Tertiary ; although some of 

 the remains attributed to the latter are undoubtedly older. 

 The Pliocene species all have a band of enamel on the tusks, 

 and some other peculiarities observed in the oldest Mastodons 

 of Europe, which are from essentially the same horizon. Two 

 species of this genus have been found in South America, in 

 connection with the remains of extinct Llamas and Horses. 

 The genus Elephas is a later form, and has not yet been iden- 

 tified in this country below the upper Pliocene, where one 

 gigantic species was abundant. In the Post-Pliocene, remains 

 of this genus are numerous. The hairy Mammoth of the Old 

 World (Elephas primigenius) was once abundant in Alaska, aud 

 great numbers of its bones are now preserved in the frozen 

 cliffs of that region. This species does not appear to have 

 extended east of the Rocky Mountains, or south of the Colum- 



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