v COLOURS OF ANIMALS 387 



yellow with black heads. In North America we might have 

 raccoons, squirrels, and opossums, in parti-coloured livery of 

 white and black, so as exactly to resemble the skunk of the 

 same country ; while in South America they might be black 

 with a yellow throat -patch, so as to resemble with equal 

 closeness the tayra of the Brazilian forests. Were such 

 resemblances to occur in anything like the number and with 

 the wonderful accuracy of imitation met with among the 

 Lepidoptera, they would certainly attract universal attention 

 among naturalists, and would lead to the exhaustive study 

 of the influence of local causes in producing such startling 

 results. 



One somewhat similar case does indeed occur among the 

 Mammalia, two singular African animals, the Aard-wolf (Pro- 

 teles) and the hyaena-dog (Lycaon), both strikingly resembling 

 hyenas in their general form as well as in their spotted 

 markings. Belonging as they all do to the Carnivora, though 

 to three distinct families, it seems quite an analogous case 

 to those we have imagined ; but as the Aard-wolf and the 

 hysena-dog are both weak animals compared with the hyaena, 

 the resemblance may be useful, and in that case would come 

 under the head of mimicry. This seems the more probable 

 because, as a rule, the colours of the Mammalia are protective, 

 and are too little varied to allow of the influence of local 

 causes producing any well-marked effects. 



When we come to birds, however, the case is different, 

 for although they do not exhibit such distinct marks of the 

 influence of locality as do butterflies probably because the 

 causes which determine colour are in their case more complex 

 yet there are distinct indications of some effect of the kind, 

 and we must devote some little time to their consideration. 



One of the most curious cases is that of the parrots of the 

 West Indian islands and Central America, several of which 

 have white heads or foreheads, occurring in two distinct 

 genera, 1 while none of the more numerous parrots of South 

 America are so coloured. In the small island of Dominica 

 we have a very large and richly-coloured parrot (Chrysotis 

 augusta) corresponding to the large and richly -coloured 

 butterfly (Papilio homerus) of Jamaica. 

 1 Pionus albifrons and Chrysotis senilis (C. America), Chrysotis sallroi (Hayti). 



