1904.] TO THE SYSTEMATIC CHARACTERS OF MAMMALS. 147 



II. Whorls^ Featherings, and Crests on the Neck., Trunk, 

 and Limbs. 



Among the numerous modifications of the arrangement of hair 

 found in Mammals in diiferent species, whorls with theii' attendant 

 featherings and crests are the most conspicuous. It is here pro- 

 posed to enumerate those among them which exhibit the greatest 

 degree of definition, and to suggest that some or all of them 

 should be dealt with in the description of the species and genera 

 in which they are found. It is not necessary here to enter into 

 the theory of the origin of these phenomena or their interpretation, 

 but only to take them as they are found on the pelage of hair- 

 clad mammals and to show their taxonomic value. Among the 

 lai-ge numbei' of these phenomena found in various groups, many 

 are casual in their appeai'ance, rudimentary, and uncei'tain. But 

 there are many the development of which is completed, and these 

 constitute the class here considered. Wide investigation of them 

 brings out the fact that a whorl is in process of further develop- 

 ment, under conditions favourable to that development. Thus a 

 whorl found alone may be looked upon as about to be projected 

 into a feathering, and a whorl and feathering found together as 

 about to be terminated, in a later stage, by a ridge or crest, which 



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