into which the wing's color softly blends, is a perfect match for the dim reflec- 

 tions of vegetation at the water's edge. Thus the Purple Gallinule's costume 

 seems to be a picture of the entire surface of a little pool among the reeds. 

 It largely lacks obliterative shading, and its pattern is to some extent of 

 the 'ruptive' type, the 'break' occurring between the dark-purple underside 

 and flanks and the bright-blue wings. This makes the sky reflection seem 

 to stop short, as if against the shadow of a water plant, while the purple pic- 

 tures a darkly and graduatedly shaded portion of the pool. A kindred type 

 of coloration, but one involving true iridescence, occurs on the American 

 Green Herons (Butorides). These birds' costumes have perhaps even closer 

 affinities with that of the Wood Duck, described in Chapter XI. Both haunt 

 opener places than do the gallinules, not being dependent, as they are, on the 

 shelter of the reedy jungle. In this respect, however, the Wood Duck is in- 

 termediate between the other two, though nearer to the heron. Green Her- 

 ons frequent the reaches of open water, and avoid the reeds; but not being 

 swimmers, they are confined to the shores and shallows, and the trees and 

 bushes over them. Characteristically, then, they are birds of the edges of 

 small inland waters. Accordingly, we find them beautifully equipped with 

 water's-edge colors and patterns. Their ash-green, delicately iridescent backs 

 picture the surface of still water, faintly shimmering, and covered with a film 

 of floating dust or scum, which blurs reflections. Their necks and heads, 

 when brown (as in some of the species), match muddy patches on the bank, 

 or mud-holes seen through shallow water, or the interior brownness of the 

 trees and bushes over or beyond the water's edge, or the brown, leafy ground 

 beneath them. But it is on the herons' wings that the obliterative picturing 

 reaches its most elaborate development. Their ground-color is a soft, iri- 

 descent, water-green, and this is broidered over with a system of delicate 

 marginal stripes and bands of white and buff. These markings are so ar- 

 ranged that they imitate very closely the look of green-reflecting water rolling 

 in small ripples over golden sand — a most characteristic sight at the borders 

 of streams and ponds. The white marks depict the ripples, and the buff 



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