20 



ORTHOGENETIC EVOLUTION IN PIGEONS. 



EXPIANATION OF PLATE 4 



A. Male homer, No. 4, stray, 1900. Natural size Hayashi del., Nov. 1904. 



The male of a pair reserved to see if I could reduce chequered pattern to 3 bars. Result: could reduce to 2 

 bars, or 2 bars plus a vestigial third; that is, reduction was even for the whole wing. The 2-barred young (fre- 

 quently obtained) bred true — gave 2-barred offspring. Thus far (Dec. 26, 1904, 5 years) there have been 5 young 

 with only 2 bars and pale gray; 5 young nearly like male. The majority were intermediate to the male and female 

 parents. 



The black (of drawings) is of course misleading, for bars vary all the way between almost black and dark gray . 

 These many shades are ignored in ink drawings. But the size is given, and thin edges and very thin or pale spots by 

 dots. 



Seen at a little distance, this male appears to have only 2 dark bars. Within a few feet we notice a few obscure 

 and small vestigial chequers in the third bar and a few scattered chequers of about the same thinness in the scapulars. 

 Spots a little stronger behind and above; weaker before and below. The bars are dark gray, not so dark as in the 

 female mate. The gray ground of this male is considerably lighter than in the female. That is, with reduction of 

 chequers comes a paler gray ground as well as less dark (paler) spots. 



Measurements of first bar {Dec. 28, 1904)- 



From here on the tips of secondaries are darkened. Tips of upper web of sixth and seventh secondaries darkened ; 

 the dark tip of eight secondary includes a little of lower web; this goes on more and more for lower web of rest of 

 secondaries. 



Measurements of second bar. 



Third bar. 

 Wholly vestigial and visible as pale dots or flecks only on 5 or 6 upper feathers. 



