POPULAE HTSTOEY OP BIRDS. 
their colour helps to conceal them. The old birds keep 
fl3dng backwards and forwards^ uttering their loud and 
clamorous cries^ in order to decoy the intruder. 
The Sheathbills (Chiontdid^) form a small family of 
birds^ distinguished by their short toes, scutellated tarsi, 
and by the thick conical beak, the base of which is enveloped 
in a waxy sheath-like structure, whence the only genus has 
acquired its English name. 
The first-described species is entirely of a white colour, 
and is a native of the Falkland Islands, where it was dis- 
covered on one of Cook^s voyages. Mr. Macgillivray"^ in- 
forms us that it is there called the Rock-dove ; and that, 
from its snowy plumage, it forms a conspicuous object along 
the shores. Though not web-footed, a specimen he shot 
took voluntarily to the water when wounded, and swam off. 
Its habits are those of the oyster-catchers; and in its struc- 
ture Blainville has shown it resembles those birds, although 
at one time it was arranged with the gallinaceous birds and 
pigeons, and by some naturalists was even associated with 
the web-footed birds. The stomachs of two specimens, ex- 
amined by the naturalist of the Rattlesnake, were found to 
contain seaweed, limpets, and small quartz pebbles. 
* Voyage of the RattlesnakCj vol. ii. p. 110. 
