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