72 
IntroductioD : Variation. 
The Kingfisher of New Guinea, a curious form with a hooked bill, 
is held by Shaipe to be the lowest type of the family, and Cittwra of Celebes 
and Sangi has the nearest affinities with it, but wants the maxillary hook. 
When quite young Cittura has this hook (p. 307). Though not a feather- 
character, this point is of equal significance. 
It has been already remarked that, when the two sexes are not alike, one 
pisually the female) seems to show a lower development than the other. It is 
probable that such females preserve more ancestral features than the males, 
which have acquired more new features than have the females; yet direct proof 
of this is hard to find. Among Celebesian birds, a female of Psitteuteles meyeri 
displays, as mentioned above, a trace of the yellow ancestral wing-band; and 
the rackets of the females of Prioniturus are seldom so long as in the males. 
Indirect proof of the phylogenetic value of the female plumage is furnished 
when the young of both sexes are like the mother, for such facts as those given 
above render it pretty certain that the young tend to display ancestral characters. 
It sometimes happens that the mother and young of one species resemble the 
adults of both sexes of another species less highly developed than the male of 
the first. 
These considerations place in the hands of the student of geographical 
distribution an important and (to ourselves) new means of proof in tracing the 
land of origin of particular species or genera — provided that our supposition be 
admitted that emigrants, cut off from their native country, are more likely to 
get altered than the stayers-at-home.^) In this manner it has proved possible to 
trace the genus Lonculus (of which over 20 geographical species are known 
between India and New Guinea) as having originated in Asia, and to construct 
a genealogical tree of two main branches showing the descent of the species 
from the Asiatic P. vernalis or its ancestor, this species being supposed to have 
extended its range in process of time across the Archipelago, undergoing some 
new modification with each change of habitat, viz. with each new isolation. The 
more eastern forms now throw back by their females and young to more western 
forms, and in this manner the two branches of the genus finally converge upon 
a form like L. vernalis. The case is fully discussed, pp. 160—169 of text. 
Map VI. 
On similar grounds it is possible to trace the origin of the Blue-and-rufous 
Flycatcher of Kalao Island to Celebes. The sexes are slightly different, and 
the male of Siphia kalaoensis is the most specialized member of its group; its 
female is like the male from Djampea Island, S. djampeana\ the female from 
Djampea is like the male from Saleyer Island and Celebes, S. hanyumas., which is 
thus indicated as having emigrated first to Djampea and later from there to 
Kalao. 
In the same manner the blue back of the young of Pelargopsis melanorhyncha 
1) For proof see variation in Sangi and Talaut, antea, p. 58. 
