30 ORTHOGENETIC EVOLUTION IN PIGEONS. 



The crested pigeon of Australia (Ocyphaps lophotes) stands at the uppermost 

 limit 12 in the number of bands and in the perfection of finish. There are 11 or at 

 most 12 parallel bands crossing the wing and scapulars transversely, each bend 

 marking a single row of feathers with the regularity of zebra stripes (pi. 8, fig. A). 

 The width of these bands increases from before backward, beginning with a width 

 of about 0.5 mm. and reaching 4 to 5 mm. on the tenth band. The eleventh band, 

 located on the long coverts, is especially interesting, as it begins above with narrow 

 elements, like the preceding, but is continued, from the third or fourth feather 

 onward, by elongated chequer-like spots. This band or bar is the homologue of 

 the anterior bar in the rock-pigeon, and furnishes a standing picture of transitional 

 continuity from one character to another, at the same time settling beyond dispute 

 the direction variation has pursued. So clear and decisive is the case that one might 

 safely predict that this entire bar is destined to be reduced to the narrow-band 

 type seen in the fore part of the wing. We have only to turn to a closely allied 

 species, the white-breasted crested pigeon 13 (Lophophaps leucogaster) to find that 

 it has already realized the prediction to the full, having every chequer in this row 

 converted into a typical band-element (text-fig. 9). 



12 The short statement on Ocyphaps given here is amplified by the whole of the following chapter. — Ed. 



13 This bird is comparatively rare, and I have seen but a single pair that recently came to hand through the kind- 

 ness of Mr. Frank M. Chapman. 



Explanation of Plate 8. 



A. Wing of adult male crested pigeon, Ocyphaps lophotes. Natural size. Hayashi del., Dec. 1898. 



This bird is nearly 2.5 years old. 



First bar. — Comprises 6 secondaries and 8 tertials. The elements of the bar are long, broad spots on lower webs ; 

 iridescent; edged at tips with white. 



The iridescence vanishes on fourth feather. The lower web is about equally dark on Nos. 1 to -t, darker on No. 

 5 and slightly iridescent; iridescence brilliant on Nos. 6 to 10; only a little purple iridescence on No. 11. No spots 

 on Nos. 12 to 14. 



Second bar. — Formed of 15 long coverts: 



(1) Black narrow bar on No. 14; is of same character as on median and lesser coverts. 



(2) Homologous with the broad iridescent spots of Nos. 13 to 5. 



(3) Upper spot or bar appears on No. 14 and disappears on No. 8. 



(4) Diminishes upward and downward, being strongest in mid-feathers, Nos. 12 to 8. 

 Third bar. — Formed of 12 median coverts. 



(1) Bar consists of two parts, as seen on No. 12 and as shown in form on Nos. 10 to 2, and again on No. 1. 



(2) Bar widens in mid-feathers, but does not expand as in second bar; does expand more than in the fourth bar. 



(3) Bar of lower web on Nos. 10 to 2 is iridescent in some lights, but seen en /arc it appears deep black. Iri- 

 descence then diminishes from behind forward, and does not extend to upper web in third ami first bars. It is inter- 

 esting to find the iridescence of third bar invisible in most lights, and, when visible, sharply limited to lower web. 



The double nature of the bars is evident on nearly all the lesser and median coverts, but the lower half becomes 

 more pronounced than the upper in the second bar, and in the first bar no upper spots are seen. Here we have remark- 

 able variations in the spots. 



Fourth bar. — Formed of 11 feathers: 



(1) The bar consists of two parts, best seen on upper feathers (No. 11 ). 



(2) The lower half is iridescent, seen in favorable light. 



(3) The width of the bar is quite even and plainly narrower than third bar. 



(4) In form one can say with respect to these four bars that they become more perfect from behind forward; 

 in color brilliancy they improve in the contrary direction. 



(5) In first bar, iridescence runs from No. 11 to No. 5, Nos. 10 to 7 being the larger and more brilliant. In 

 second bar, iridescence runs from No. 13 to No. 5, Nos. 13 to 6 being the larger and more brilliant. In third bar each 

 feather is marked on both webs, except the first, and the last imperfectly on upper web. In fourth bar each feather 

 has a bar crossing both webs. The iridescence in the lower web is stronger in thud bar than in fourth. 



B. Wing of juvenal female crested pigeon, O. lophotes. Age 19 days. Natural size. Hayashi del., 



Aug. 1905. 



The ashen-gray ground-color contrasts strongly with the adult coloration (see above, fig. A). All feathers with 

 pale or white tips; black pigment concentrated immediately in front of these. 



