261 TROPICAL NATURE, AND OTHER ESSAYS. 



a ground pigeon ; l all equalling if not surpassing their 

 nearest allies in whiteness, although some of these, from 

 the Philippines Moluccas and Celebes, are sufficiently 

 remarkable in this respect. 



In the small Lord Howe's Island we have the recently 

 extinct white rail (Notornis alba), remarkably contrasting 

 with its allies in the larger islands of New Zealand. 



We cannot, however, lay any stress on isolated ex- 

 amples of white colour, since these occur in most of 

 the great continents ; but where we find a series of 

 species of distinct genera all differing from their con- 

 tinental allies in a whiter coloration, as in the Andaman 

 Islands, Duke-of-York Island, and the West Indies, 

 and, among butterflies, in the smaller Moluccas, the 

 Andamans, and Madagascar, we cannot avoid the con- 

 clusion that in these insular localities some general cause 

 is at work. 



There are other cases, however, in which local influ- 

 ences seem to favour the production or preservation of 

 intense crimson or a very dark coloration. Thus in the 

 Moluccas and New Guinea alone we have bright red 

 parrots belonging to two distinct families, 2 and which 

 therefore most probably have been independently pro- 

 duced or preserved by some common cause. Here, too, 

 and in Australia we have black parrots and pigeons ; 3 

 and it is a most curious and suggestive fact that in 

 another insular subregion that of Madagascar and the 

 Mascarene Islands these same colours reappear in the 

 same two groups. 4 



1 Monarcha verticalis, Diceum eximium, Artamus instgnis, Pldogainas 

 johannce. 



Lorius, Eos (Tricboglossidae), Echctus (Palseomithidae). 

 3 Microglossus, Calyptorlynchus, Turaccena. * Coracopsis, Alectramas. 



