50 NEW ZEALAND BIRDS. 



mandibles Tvoiild form a tube through which water and insects could 

 be drawn up, as water is sucked up Ijy a syringe. As the flexure of 

 the bill is lateral, the bird is enabled to follow up retreating insects by 

 making the circuit of a water-worn stone with far greater ease than 

 if it had been furnished with the straight beak of the Plover, or the 

 long flexible scoop of the Avocet. The inspection of these specimens 

 must clear away any little cloud of doubt that might remain on the 

 minds of persons unfamiliar with the bird, and convince them that 

 this singular form of bill, so far from being an accidental deformity, 

 is a beautiful provision of Nature, which confers on a Plover-like 

 bird the advantage of being able to secure a share of its food from 

 sources whence it would be otherwise unattainable.^' — Potts. 



" But there is another feature in the natural history of this species 

 that is deserving of special notice. As already described, the fully 

 adult bird is adorned with a black pectoral band, which, in the male, 

 measures '75 of an inch in its widest part. Now it is a very curious 

 cireumstanee that this band is far more conspicuous on the right- 

 hand side, where, owing to the bird's peculiar habit of feeding, there 

 is less necessity for concealment by means of protective colouring. 

 This character is constant in all the specimens that I have examined, 

 although in a variable degree, the black band being generally about 

 one third narrower and of a less decided colour on the left side of the 

 breast, from which we may, I think, reasonably infer that the law of 

 natural selection has operated to lessen the colouring on the side of 

 the bird more exposed to Hawks and other enemies whilst the 

 Anarkyncus is hunting for its daily food. There can be no doubt 

 that a protective advantage of this sort, however slight in itself, Avould 

 have an appreciable effect on the survival of the fittest, and that, 

 rllowing sufficient time for this modification of character to develop 

 itself, the species would at length, under certain conditions of exist- 

 ence, lose the black band altogether on the left-hand side." — Buller. 



Steepsilas. Illiffer. 



Bill, not longer than the head, lateral margin of both mandibles turned upwards ; first 

 quill, longest ; tarsij us long as the middle toe ; hind toe present. 

 All parts of the world. 



64. Strepsilas interpres. L. 



TUENSTONE. 



Above, blackish-brown ; throat, abdomen, and over the tail, white ; breast, brownish- 

 black ; tail, white, with a broad brown bar near the tip ; bill, black ; legs, red ; shafts of 

 the quills white (winter plumage). 



L., 8-75 ; W., 5-75 ; B., 1 ; T., 1. 



Effff. — Grejish-olive, with brown spots (Tcmminck). 



Sab. — Canterbury Province. Found all over the world. 



