i62 STUDIES IN THE EVOLUTION OF ANIMALS 



between the rosette blotches indicates the enclosed space, but the 

 Jaguar skin of Fig. 4 sufficiently shows that the enclosed spaces of 

 the rosettes are of a different and deeper shade.^ In some Ocelots 

 the enclosed space is quite brown. This difference of colour would 

 certainly indicate that in the nerve-centres there was some differ- 

 ence, although of an atomic character, in the cells which regulate 

 the colour of the inside and of the outside of the rosettes. In all 

 probability the atomic difference is of the same nature as that 

 which caused a large plate to be deposited in the centre of the 

 armour-rosette and a ring of small ones outside it. What we have 

 to note is that there is a difference between the inside and outside 

 of the Jaguar and Ocelot rosettes. 



Why this is so we do not know, any more than we know why 

 one Horse is dun, another bay, a third brown or black ; why a dun, 

 a bay, a dark grey, and even a black Horse sometimes has a pure 

 white mane and tail, and so forth. 



To sum up, in the existing Jaguar coloration we have the 

 following elements, no doubt much modified from those of the 

 ancestral Jaguar : — 



(a) We have the general ground colour of a rich tan between 



the rosettes ; 

 {b) We have the spots more or less fused, which make up the 



polygonal rings of the larger rosettes ; 

 {c) We have the enclosed space, which is often of a darker hue 



than that of the ground spaces ; 

 {d) We have those curious central black spots. 

 Now I have elsewhere mentioned that tan colour is interchange- 

 able with either white or black, and so we have the general colour 

 changed into either brown or black in the black Jaguar. 



'^ In the photograph this is decidedly shown, but in the illustration the difference of 

 colour is not so clear. 



