RECENT LAND MAMMALS OF WESTERN NORTH AMERICA 137 



Secondly, we have conservatives and liberals, or lumpers and 

 splitters, among students of Recent mammals. Ellerman and 

 Morrison-Scott (1951) tend to be conservative for genera and species 

 while Cabrera and Yepes (1940) are quite liberal with the number 

 of genera that they recognize. Miller and Kellogg (1955) include 

 the findings in the latest revision of each group, with no critical 

 analysis of their own, so their list is a mixture of conservatism and 

 liberalism. In some groups, such as the Grizzly Bears, the last 

 authors, following Merriam's 1918 revision, list no fewer than 69 

 species for North America. They also give the black bear different 

 generic rank (Euarctos) from the grizzly {Ursiis). In 1953, two years 

 before the list by Miller and Kellogg appeared, Erdbrink included 

 all the Recent bears in the one genus Ursus, and all the North 

 American species of the grizzly, along with those from Asia and 

 Europe, in the one species arctos. These two works represent extremes 

 in the evaluation of names. It must be frustrating to the non- 

 taxonomist to see two such treatments within two years by two 

 different authorities. It is also frustrating to the taxonomist who is 

 attempting to apply a formula for taxonomic resemblance between 

 North America and Asia. 



Thirdly, and somewhat related to the two previous difficulties, 

 is the fact that some kinds are considered in the literature to be 

 conspecific or congeneric while others, probably just as closely 

 related, are not. Some examples of species that are now considered 

 by some, at least, to be conspecific for North America and Asia are: 

 a shrew {Sorex pacificus), the gray wolf {Cams lupus), Arctic fox 

 (Alopex lagopus), wolverine {Gulo gulo), two weasels (Mustela 

 erminea and M. ?iwalis), moose {Alces alces), a ground squirrel 

 (Citellus undulatus), and two voles {Microtiis oeconomus and 

 Clethrionomys rutilus). Such kinds as the red fox (Vulpes), marten 

 (Martes), river otter (Lutra), lynx {Lynx), lemmings {Dicrostonyx 

 and Lemmus), chipmunk {Eutamias), and several voles and shrews 

 are considered to be distinct species, at least in the literature. 

 In a case like this, the counting of names without some evaluation 

 may give a false impression. 



A fourth problem, but not a difficult one, is what category to 

 use. If we simply count the species listed for western North America 

 and for northeastern Asia, we come up with about 229 and 160, 

 respectively. On the basis of species names, North America would 



