14 



ORTHOGENETIC EVOLUTION IN PIGEONS. 



EXPLANATION OF PLATE 2. 



Adult Columba livia, uniform gray, third bar. Photographed and spots measured Nov. 1898. 

 There are 14 secondary and tertial coverts (primaries, 10). 



Left third bar (wholly concealed); measurements in millimeters. 



Feather 14. A blackish spot on upper edge and just a last trace of one on lower edge. Spots dusky gray; greatest 



width of spot, 6 mm. long by 1.5 mm. 

 13. Upper spot, 6 mm. by 1.5, about same as in 14; lower spot so reduced that a magnifying glass is necessary 



in order to see the slight touch of dusky at lower edge. 



12. Upper spot reduced to last touch, recognizable only by aid of magnifying glass; lower spot absent. 

 11. None on either side. 

 10. No upper; lower spot, 3 by 1. 

 9. Spot (lower), 3 by 1.5. 

 8. Spot (lower), 3 by 1.75. 



7. Spot (lower), 5.5 by 3.25 (widest and most conspicuous of all). 

 6. Spot (lower), just a dusky trace. 

 5. Spot (lower), 5.5 by 1.5. 

 4. Spot (lower), 7.5 by 1.5. 

 3. Spot (lower), just a trace. 

 2. Spot (lower), no trace. 

 1. No trace. 



A third bar, wholly concealed, in this pigeon is suggestive. It is much the same as 1 have several times found in 

 the first plumage of some young domestic pigeons. The rock-pigeon of (uniform gray wing) then exhibits in adult 

 plumage the juvenile condition of domestic pigeons. 



Note, too, that two upper feathers exhibit double spots, at least in traces. The upper spot diminishes down- 

 ward is lost on No. 11. Of the lower spot there is only the minutest trace on two upper feathers; it is absent on 

 the next two; and then, as the only spot, it increases downward, with a maximum on No. 7. 



The larger spots are in lower half of series, and this agrees in a general way with the young domestic. 

 Notice for comparison chequered domestic (pi. 5), where the feathers of the third bar all have two spots instead 

 of one. 



