378 BIRDS OF AUSTRALIA. 



settlement at Port Essington, where, however, it is very rare ; 

 it is also occasionally met with in Western Australia. In this 

 bird we have another beautiful representative of a species 

 common to Europe and India, the Nyroca leucoplithalmos, 

 both birds having white eyes and a similar style of plumage ; 

 the Australian species differs, however, from its near ally in 

 having a lighter-coloured plumage, and less of the chestnut 

 hue ; it is also a much larger bird. Quiet reaches of rivers 

 where the water runs slowly, bays and inlets of the sea and 

 lagoons, are among its favoiu-ite places of resort. As may be 

 supposed, it is a very excellent diver, and gains much of its 

 food beneath the surface of the water, readily descending to 

 the bottom in search of small mollusca, crustaceans, insects, 

 and aquatic plants. 



The only outward difference between the sexes consists in 

 the female being rather smaller than the male, and somewhat 

 less bright in colour. 



The male has the general plumage chestnut-brown ; across 

 the breast a broad band of brownish white ; secondaries white 

 at the base, forming a conspicuous mark across the wing, 

 and tipped with bronzy brown ; basal portion of the inner 

 webs of the primaries and under tail-coverts white ; bill 

 black, with a band of blue-grey near the tip -, irides white ; 

 fore part of the tarsi lead-colour ; hind part of the tarsi and 

 the webs blackish brown. 



Why is it that so many of the Australian birds have white 

 irides ? What can be the object and intention of this de- 

 parture from the normal rule ? The following are a few of 

 the instances in which this peculiarity occurs : — the Crow, 

 Grallina, and Struthidea ; the beautiful Marsh Gull, of the 

 genus Chroicocephalus ; and the present bird. 



