228 Mr. J. Whitehead on Birds 



are almost white on the undersidcj and liave the white streak 

 ou the mantle very distinct. Mr. Grant believes these differ- 

 ences in Luzon birds to be due to age, the most adult birds 

 being the whitest ; but I do not think that he would have 

 described the coast-birds as immature if he had not first seen 

 and described the highland specimens. 



In my opinion this difference of coloration is entirely 

 due to altitude, and coast-birds, be they ever so old, would 

 never become white. This is a most interesting instance of 

 colour-evolution, as the intermediate steps are not wanting 

 in which D. mnochlamys of the Lvizon coast-districts becomes 

 D. mesoleuca as it reaches higher altitudes. 



That the Negros Nuthatches show no change in plumage 

 as they reach higher elevations is not so strange as it may at 

 first seem. In Negros the mountains form a volcanic back- 

 bone of less than 7000 feet ; while in Luzon we find high- 

 lands of greater area than the entire island of Negros, of 

 much greater altitude, and of apparently greater antiquity, 

 isolated from the coast by barren ranges of grass-covered 

 hills to the west, and to the east and south by broad, treeless, 

 grass- covered plains, thus assisting to isolate the highland 

 forms. The Negros Nuthatches might go up and down these 

 mountain-sides in a day without ever quitting the forests, and 

 therefore none of the birds gain distinctive coloration 

 through lengthened isolation at high elevations. 



Iris straw-yellow ; orbital skin and bill greenish yellow ; 

 feet olive- green. 



141. Dendrophila lilacea Whitehead. 



Detidrophila cenochlamys Grant, Ibis, 1897, p. 235. 



Dendrophila lilacea Whitehead, Bull. B. 0. C. vi. p. xlix. 



I described the specimens of Dendrophila collected by me 

 in Samar and Leite under the name of D. lilacea, as they are 

 quite distinct in the coloration of the underparts from the 

 birds collected in Negros, being of a bright glossy lilac, 

 perhaps nearer D. corallipes of Borneo. D. lilacea occurs also 

 in Basilau, but I have not seen any examples from Mindanao. 

 [Cf. Ibis, 1897, p. 451.) 



