THE DIVISIBILITY OF CHARACTERS. 



215 



To show how this divisibility of specific characters works out when we carry- 

 it a Httle further, we will consider another pair of birds that I have worked with a 

 little longer. The Surate turtle-dove {Spilopclia siiratensis) is illustrated in colors 

 in pi. 24. Attention may be especially called to the well-defined and peculiar 

 character of the spots on the neck and to the central dark median streak of the 

 wing-feathers. The feathers of the neck have a dark base and a white tip, which 

 give the neck a sort of speckled appearance, white and black both showing, owing 

 to the fact that each feather is split at the tip. The feathers are arranged in rows, 

 and there is a larger number of rows than in the Japanese turtle-dove. The species 

 suraiensis has advanced considerably bcj'ond the ancestral turtle-dove, both in 

 the neck-mark and in the wing-feathers. In the Japanese bird is seen a simple 



There are 11 rows of feathers in the 

 neck-mark, as in the band-tail {C.fasciala 

 text-figure 5), and some additional front 

 feathers are affected. The light tips are 

 seen on the lower 6 rows, which corre- 

 spond to the spot on the turtle-dove. 

 The tips are whitish or light buff, as thr 

 sample feather shows. A dark or black- 

 ish area follows the light tip; this corre- 

 sponds to the dark area in feathers of 

 turtle-doves. 



\ 



|S<-^1 





a^ ,|i|||lll»|||%^- 



Text-figure 6. — Neck-mark of adult wood-pigeon, Columba palumbus. Natural size. G. A. Wilson del., 1900. 

 Hayashi del. separate feather. 



dark center with a light reddish edge. In suratensis the dark center has been 

 reduced to a narrow median streak which is somewhat enlarged towards the end.'' 

 The female Surate turtle of the illustration is the mother and a ring-dove* the 

 father of the hybrid shown in pi. 25. The first thing to notice concerning it is 

 that its size is about that of the two parent species, which are nearly equal in size; the 

 hybrid therefore agrees in this respect with both parents. The bird as a whole is 

 considerably lighter than the mother, considerably darker than the father. But 

 in order to see how neatly an intermediate character comes out, one may best exam- 

 ine the feathers on the neck. Here it will be found that the size of the spots is 

 somewhat "reduced" as compared with the mother, but considerably "enlarged" 



'The form nearest related to Spil. suratensis is the Chinese turtle-dove {Spil. chinensis), which has completely 

 obliterated this median streak; its neck-mark, like that of suratensis, covers many rows, meets with its opposite on 

 the back of the neck, and is composed throughout of white-tipped, bifurcated feathers. (In text-fig. 10 these points 

 are made clear, and also a comparison of this with other forms is made possible. — Editor.) 



* This bird was of "blond" color but an alba-risoria x risoria-alba hybrid. — Editor. 



