SPOTS AND STRIPES IN MAMMALS 33 



Whether these laws hold good for other groups of ver- 

 tebrates, it is not within the scope of the present article 

 to inquire, and attention will accordingly be concentrated 

 on mammals. If they be true, we should, prima facte, 

 expect to find a large number of longitudinally striped 

 forms among the lower members of the class ; while those 

 of intermediate grades of evolution would be spotted, and 

 the higher types either transversely striped or uniformly 

 coloured. This, however, could only be the case, as a 

 whole, if all mammals formed one regularly ascending 

 series ; whereas, as a matter of fact, they form a number 

 of divergent branches, each containing specialised and 

 generalised forms. The inquiry is thus rendered one of 

 extreme complexity, although there ought, if the theory 

 were true in its entirety, to be a considerable number of 

 longitudinally striped species among the lowest groups of 

 all. Unfortunately, palaeontology, from the nature of the 

 case, can afford us no aid, which very materially adds to 

 the difficulty. It may be added that in Prof. Eimer's 

 scheme no distinction is drawn between light and dark 

 markings — that is to say, between the total disappearance 

 of pigment and an ultra-development of the same — and 

 it is obvious that this may be of such prime import- 

 ance that these two types of coloration may have nothing 

 whatever to do with one another. Nevertheless, we 

 may provisionally consider light and dark stripes and 

 light and dark spots as respectively equivalent to one 

 another. 



With regard to uniformly coloured animals, there can be 

 no question as to the truth of the theory, since the young 

 of so many animals, such as lions, pumas, deer, pigs and 

 tapirs show more or less distinct striped or spotted mark- 

 ings, which disappear more or less completely in the adult. 



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