264 TEOPICAL NATURE, AND OTHER ESSAYS. 



a ground pigeon ; ^ 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,^ and which 

 therefore most probably have been independently pro- 

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

 9,nd in Australia we have black parrots and pigeons f 

 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.* 



^ Monarcha verticalis, Diceum eximiuniy Artamus insignis, Fhlogcenas 

 johaimoe. 



Lorius, Eos (Trichoglossidse), Eclecfns (Palseornithidae). 



Microglossus, CalyptorTiynchus^ Turaccena. ^ Coraco^sis, Alectrcenas. 



