CHAP. XIV COLOURS OF MAMMALS 287 



the decomposition products of hemoglobin, unless 

 melanin be one of these, are of no importance in pro- 

 ducing external colour ; nor do the lipochromes ever 

 appear to occur in the epidermis or cuticle. Optical 

 colours except white are rare in mammals, but true 

 metallic colours occur in the Cape golden mole 

 {Chrysochloris). In this little insectivore the fur 

 especially of the upper surface displays " a brilliant 

 metallic lustre, varying from golden-bronze to green 

 and violet of different shades " (Flower). The exact 

 causation of the colour appears to be unknown. 



In mammals generally the beauty of the colour- 

 ing is dependent upon the unequal distribution of 

 the melanin pigments, which are very frequently so 

 arranged as to produce the effect of stripes or spots. 

 There are several papers upon the origin, relations, 

 and meanings of these markings, but all are too 

 purely theoretical to demand detailed notice here. 

 An account of them will be found in the works of 

 Wallace, Eimer, Bonavia, and others. 



Among the general colour characteristics of 

 mammals, we should notice the tendency of certain 

 variations to recur constantly in many different 

 orders ; such are the deepening of the tint (melan- 

 ism), the disappearance of the pigment (albinism), 

 the prevalence of a sandy colour in mammals in- 

 habiting deserts, and so on. Melanic varieties are 

 seen not infrequently in the leopard {Felis pardus), 

 especially in Southern, Asia ; they seem to occur 

 quite sporadically. A very interesting point about 

 these black leopards is that, in certain lights, the 

 markings characteristic of the leopard can be seen 

 on the black ground like the pattern on " watered 



