THE ORIGIN AND RELATIONSHIP OF THE ROCK-PIGEONS. 



57 



stands at the opposite extreme, with not a single black chequer left on the wings, 

 and is therefore to be classed as the latest branch of the family. Intermediate 

 stages, with few to fewer spots, are seen in the two genera, Zenaida (pis. 83 to 87) 

 and Zenaidura (pi. 19, Vol. II). 



The white-winged pigeon {Melopelia leucoptera) is a most instructive form. 

 Although a much more highly accomplished bird in the arts of display of form, 

 feathers, and voice than the mourning-dove, it has suffered a complete effacement 

 of the chequers it once possessed in common with other members of the family. 

 Indubitable proof of this is to be seen in the juvenal feathers, which, in some cases, 

 exhibit a few pale vestigial chequers (text-fig. 14) in the last row of long coverts 

 at points where the chequers are usually best developed in chequered species. 



Text-figure 14. — Left wing of juvenal white-winged pigeon, Melopelia leucoptera, age 25 days. 



Natural size. Hayashi del., May 1899. 



Rudimentary (obsolescent) spots are shown, but so nearly faded out and so nearly covered that one would not 

 notice them unless looking especially for them. Color dark gray; in shape they are pointed posteriorly. The spot is 

 elongated along the lower margin of the feather. There are only a few of them; three or four of the longer tertials 

 have long, narrow edge streaks, completely out of sight under the longer coverts. I found four spots on the upper 

 longer coverts, the lower of which was covered and is not seen in figure. The next row of coverts has three or four 

 spots, rather smaller and more obscure, at about the same level as spots in long coverts. 



The secondaries are quite dark, with white edge and tip. This is the lower half of the first bar. The upper half 

 of this bar is represented by the three or four covered spots of the tertials. I could find no other spots on the coverts 

 or scapulars. 



When the feathers are mounted on white board, one can scarcely make out even rudimentary spots, yet there are 

 slight traces. 



I predicted that the young of this species, which in the adult has no spots, might show traces of spots. This is 

 a good demonstration of my theory that the ancestral pigeon had elongated pointed spots. 



Another striking proof is to be found in the coverts and scapulars of the adult 

 bird, where we find, on lifting the feathers, distinctly outlined impressions, corre- 

 sponding in shape and position with reduced spots, but from which the black 

 pigment has disappeared. These vestigial outlines, structural^' defined, were first 

 noticed in a female bird of a dark shade captured " in Jamaica. The outlines were 

 here more perfect than in lighter birds obtained from Arizona and California. 



Similar imprints are present in the mourning-dove, and here their identification 

 as marks formerly filled out with black pigment is freed from every shadow of 

 doubt by chequers in all stages of obliteration. They show us that chequers are 



11 By Dr. Humphreys. 



