Introduction: Variation. 
7/ 
9. Male unlike female: young female like adult female, young male 
peculiar [Microstictus partly; Dryohates ^e^iopicus: 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 melanorhyncha and 
P. dichrorhyncha 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 Trichoglossus 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 helow. 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. 807, 808 of text). 
The Parrots of the genus Prioniturus have the two middle tail-feathers 
furnished with long projecting rackets. A’oung 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, Merula 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). 
