CHAP. XIV 
COLOURS OF MAMMALS 
287 
the decomposition products of haemoglobin, 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. Melanie 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 
