OF LIFE IN GENERAL. 329 



locality. Panthers and ocelots, indeed, showed a very 

 considerable increase in size on passing southward. 

 Still the increase in size of Carnivorous Mammals on 

 passing from South to North may be taken to be a 

 very general rule. In addition to the Felidse men- 

 tioned, this relation is well shown in the badger, mar- 

 ten, wolverine, and ermine. 



Of other Mammals, the relationship between locality 

 and size is well shown by members of the deer family, 

 the Virginia deer affording an especially striking in- 

 stance. The Glires (squirrels, marmots, mice) also 

 increase, as a rule, towards the North. For instance, 

 the northern race of flying squirrels is half as large 

 again as the southern, but these two extremes are con- 

 nected by a complete chain of intermediate forms. 

 As in the case of birds, mere size of body is not the 

 only characteristic which varies with locality. The 

 ears and the feet may undergo considerable changes in 

 addition. Thus in mammals with large ears, such as 

 wolves, foxes, some of the deer, and especially the 

 hares, there is often a striking increase in the size of 

 these appendages on passing from North to South. 

 The ears of the little wood hare (Lepus sylvaticus), 

 found in Western Arizona, are nearly twice the size 

 they attain in the variety found in more easterly and 

 northerly regions. Again, in Lepus callotis the ear is 

 one-third to one-fourth larger in examples obtained 

 from Mexico than in those from Wyoming, whilst the 

 little brown hare (L. trowbridgei) shows a similar in- 

 crease in the size of the ear in the south. 



Darwin * has collected several cases in which climate 

 * " Animals and Plants," ii. p. 268. 



