MAMMALS. C19 



been transmitted equally, or almost equally, to both sexes; 

 and we may now inquire how far this view applies to mam- 

 mals. With a considerable number of species, especially 

 of the smaller kinds, both sexes have been colored, inde- 

 pendently of sexual selection, for the sake of protection; 

 but not. as far as I can judge, in so many cases, nor in so 

 striking a manner, as in most of the lower classes. Audu- 

 bon remarks that he often mistook the muskrat,* while 

 sitting on the banks of a muldy stream, for a clod of earth, 

 so complete was the resemblance. The hair on her form is 

 a familiar instance of concealment through color; yet this 

 principle partly fails in a closely allied species, the rabbit, 

 for when running to its burrow, it is made conspicuous to 

 the sportsman, and. no doubt, to all beasts of prey, by its 

 upturned white tail. No one doubts that the quadrupeds 

 inhabiting snow-clad regions have been rendered white to 

 protect them from their enemies, or to favor their stealing 

 on their prey. In regions where snow nevei lies for long, 

 a white coat would be injurious; consequently, species of 

 this color are extremely rare in the hotter parts of the 

 world. It deserves notice that many quadrupeds inhabit- 

 ing moderately cold regions, although i..ey do not assume 

 a white winter dress, become paler during this season; and 

 this apparently is the direct result of the conditions to 

 which tht-y have long been exposed. Pallas f states that in 

 Siberia a change of this nature occurs with the wolf, two 

 species of Mustela, the domestic horse, the Eqnus Jtciiiiomts, 

 the domestic cow, two species of antelopes, the musk-deer, 

 the roe, elk and reindeer. The roe, for instance, has a red 

 summer and a grayish- white winter coat; and the latter 

 may, perhaps, serve as a protection to the animal while 

 wandering through the leafless thickets, sprinkled with 

 snow and hoar-frost. If the above-named animals wore 

 gradually to extend their range into regions perpetually 

 covered with snow their pale winter coats would probably 

 be rendered, through natural selection, whiter and whiter, 

 until they became as white as snow. 



Mr. Reeks has given me a curious instance of an animal 



'-Fiber zibo.thicus, A minium and Bacliman, ''The Quadrupeds of 

 North America," 1846, p. 109. 



f " Novae species Quadruped um e Glirium ordine," 1778, p. 7. 

 What i have called the roe is the Caprevlux aibiricus isubecaudatus of 

 Pallas. 



