162 
Birds of Celebes: Psittacidae. 
parrots abound, to India, or did it range in earlier times, when the whole was 
one mass of land, throughout the then Eastern Continent and was more or less 
differentiated, split into species, after the formation of the Archipelago?^) 
The conclusion seems unavoidable — and this remark is made after carrying 
the matter in mind for a period of abont five years — that Loriculus (in some 
cases at least) extended its range by flight across the sea. 
In addition to this we must state, as necessary to the following argument, 
that emigrants get altered more than stayers-at-home. It may in a cer- 
tain sense be compared to the axiom of Euclid; “If unequals be added to equals, 
the wholes are unequal”, the unequal condition in the zoological case being 
the new conditions of existence for the colonists. 
Further, it may be stated that there is much reason to assume that the 
plumage of young birds is often ancestral in character. In proof of 
which it could hardly be possible to point to a better case than the racket 
tail-feathers of Prioniturus^ which in the young clearly show an initiatory stage 
of development (see plates with figures and remarks thereon in our Intro- 
duction), and other good cases among Celebesian birds are the blue back in 
the immature Pelargopsis melanorhynchus^ the traces of a yellow wing-band in the 
young Trichoglossus fneyeri^ the Kestrel-like plumage of the young of the Hawks 
Accipiter rhodogaster and Spilospizias trmotatus^ the identical young plumage of 
the Hawk-eagle Spizaetus lanceolatiis and the Honey-buzzard, Perms celehensis. 
In many cases among birds the female shows a minor differentiation than the 
male, for instance, again, Prioniturus \ very rarely a higher one (Turnix). As 
Gadow remarks (Newton’s Diet. B. 1893 p. 100): “Instances, too well known 
to be repeated here, show clearly how the changes of bygone ages of the an- 
cestors are recapitulated in the yearly moult of the growing individual until with 
maturity its present stage of perfection is reached”. The very utmost caution 
should, however, be used in making use of this principle, for all sorts of disturb- 
ing side-influences forbid of its acceptation as thorough-going: sometimes, for 
instance, as in some of the Kingfishers, the young display no differences from 
their parents, sometimes the differences seen in them seem to be of a special 
protective or other character rather than ancestral, sometimes the mother’s influence 
preponderates though her characters may be more recent than those of the father 
(for instance, in the genus Edoliisoma), sometimes, when the male seems to be 
the less differentiated, the young take after him ( Turnix)^ sometimes the male young- 
one is like the father, the female young one like the mother (for instance, 
Motiachalcgon, Cittura, Eclectus). It is excessively difficult to form an opinion as 
to whether the dress of a young bird is ancestral in character dr not; one feels 
justified in doing so only when the young throws back very plainly to some 
form which is existing to-day. 
1) We do not take into consideration the possibilitj^ that the genus spread out east and west from one 
of the central island groups, as there appear to be no indications for such a supposition. 
