Introduction: Variation. 7/ 



9. Male unlike female: young female like adult female, young male 

 peculiar iMicrostictus Tpartly; Diyobates and Xenopicus: Keeler, p. 224). 

 It seems to be a very true remark of Darwin's that these several classes 

 graduate into one another. 



Ancestral characters. — At the present time much interest turns on the 

 difficult question of the manifestation of the past history of the race occasionally 

 to be read in the plumage of the young or in the less highly developed sex. 

 Among Celebesian birds the following are some of the more interesting and 

 undeniable examples of ancestral indications in the young. 



The Kingfishers of the Oriental genus Pelargopsis have the lower back and 

 rump blue, except in the Celebesian area, where Pelargopsis melanorhyticha and 

 P. dkhrorhyncha have these parts buff. The young of P. melanorhyncha is known 

 to have the parts in question blue — proof that the species was once so coloured 

 (pp. 269, 270 of text). 



The Lories of the subgenera Trichoglossxis typical and Psitteuteles have a 

 yellow (or red) band across the under side of the wing, except in Trichoglossus 

 ornatus and Psitteuteles meyeri of Celebes, and P. jlavoviridis of Sula, which have 

 the wing uniform below. Traces of yellow, where the band should be, are often 

 seen in young individuals (occasionally in an apparently adult female) of P. meyeri, 

 and now and then in the young of T. ornatus, proving that these two species 

 once possessed the wing-band (p. 126 of text). 



The Stork, Dissoura episcopus, has no contour-feathers, but only down, on 

 the sides of the head and on the neck, though it is not to be doubted that it once 

 had these parts feathered. The young has the sides of the head feathered, and 

 some feathers of blackish brown are produced on the neck, but they soon fall 

 out. These feathers indicate what the species was like at some period of the 

 past (pp. 8j07, 808 of text). 



The Parrots of the genus Prioniturus have the two middle tail-feathers 

 furnished with long projecting rackets. Young birds before the first moult dis- 

 play attenuated projecting ends or half-formed rackets (see pi. V, figs. 1, 2), 

 showing, according to the argument pursued below, p. 74, an earlier stage in 

 the formation of these growths. 



The Tree Duck, Dendrocygna guttata, has round white spots on the flanks; 

 in the young these spots take the form of stripes similar to those of D. arcuata 

 at all ages; a proof that the round spots are a recent development (p. 872). The 

 Blackbird, Menda celehensis, when young is spotted like a Thrush (see pi. XXXV). 



The little slate-and-vinous Hawks, Accipiter rhodogaster and sulaensis and 

 Spilospizias trinotatus are totally different when young, resembling Kestrels 

 ( Tinnunculus) ; and the Pigeon, Chalcophaps, in first plumage has no resemblance 

 to the adult (an unusual circumstance among Pigeons), but has the coloration 

 of the Pigeon- genus Macropygia. It appears hardly possible to doubt that these 

 are ancestral indications (pp. 25, 26, 650, 652 of text). 



