Proceedings of the British Association. 357 



which are common to both North America and Europe ; though 

 possibly a closer acquaintance with some which are at present con- 

 sidered identical, may enable us to establish some distinction between 

 them. The generic forms of North America are the same as those 

 of Europe, excepting in a very few cases, which belong to the South 

 American group. A few of the more northern forms also cross the 

 Isthmus of Darien to the south. — In the family of Plantigrada, two 

 of the four bears of North America are undoubtedly peculiar to the 

 New World ; and one of these is the most northerly quadruped it 

 contains. The American Glutton, or Wolverine according to Cu- 

 vier, is identical with that of the Old World. Among the Digiti- 

 grada, the range of the Mustelse is limited southwards to the north- 

 ern or middle district of the United States. Whether any of the 

 American and European species of this genus be really identical, is 

 involved in great uncertainty. Of the three otters of North Amer- 

 ica, one appears to be identical with that of Europe ; and another, 

 if correctly identified as the Lutra Brasiliensis, has a most exten- 

 sive range, from the Arctic Sea through great part of South Amer- 

 ica. Eight species of the genus Canis are found in North America ; 

 but there is great difficulty in distinguishing the species, and in iden- 

 tifying them with any of those of Europe. The domestic dog 

 breeds with the wolf and fox, and their offspring is prolific. Eight 

 species of the genus Felis were mentioned by Dr. Richardson, three 

 of which extend from South America into the south western territo- 

 ries of the United States ; and some of the others are still doubtful 

 as North American species. The nine species of Amphibia found 

 in North America, are mostly common to the northern seas of the 

 Old and New Worlds ; the genus Otaria alone being confined to the 

 North Pacific ; and even these range to the Asiatic coast. The 

 specific identity of som.e of the seals is involved in very great doubt. 

 In the order Rodentia, there have been between seventy and eighty 

 species discovered ; and here North America surpasses every quar- 

 ter of the globe in the abundance and variety of form which these 

 animals assume. The squirrels are not yet satisfactorily determined. 

 The marmots are numerous, except in the subgenus Spermophilus. 

 There is only one which may possibly be common to the New and 

 Old World. There is only one of the restricted genus Mus, which 

 is unequivocally indigenous to North America ; and this closely re- 

 sembles the European M. sylvestris. Other species have been in- 

 troduced from the opposite side of the Atlantic. 



