Vlll 
INTRODUCTION. 
been denominated omnivmrous, by an indefatigable explorer- of the 
operations of nature. The sub-division is therefore also liable to exeeption, 
as necessarily must be every attempt to fetter within limits, fixed by man, 
the innumerable varieties of the productions of nature. Some birds are 
entirely inseetivorous, others live on berries alone, others feed on fishes, 
and some indiseriminately devour flesh, grain, berries, and insects. The 
feet, however, form an immediate and obvious distinction of land birds, 
from water fowl. Those that spend most of their lives on the water, 
have in general webbed feet ; yet there are some that swim and dive with 
facility, gracefulness, and celerity, as the Water Ouzel, the Water Rail, the 
Water Hen, and the Coot, which are either without the web that distinguishes 
water fowl, or possess in its stead, a thin narrow membrane skirting the toes. 
A small division has since been made, for the purpose of comprehending 
such as are not strictly either water fowl, or land birds, under the name of 
WADERS. The chief characteristics of which are, long and naked legs, 
long or broad bills, intersected with many nerves, large eyes, and short 
tails. But the Plover tribes, in many instances, do not resemble these. 
Granivorous birds have been peculiarly denominated, animals with 
muscular stomachs : although all animals possess stomachs with powerful 
muscles ; yet, in these birds, their strength and vigor are in a far superior 
degree. They are commonly said to have two stomachs, but this is not 
consistent with the fact. Neither the crop, nor the bulbous expansion of 
the oesophagus, or gullet, just above the gizzard, is properly a stomach, 
but merely a dilatation of that tube. The former expansion, (the crop 
or craw)' a little below the entrance of the gullet, forms a membranous 
sack, or capacious reservoir, in the common fowl, pigeon, and a 
few others, in which their food is macerated by the action of the oesopha- 
geal liquor, which is a whitish, dense, and viscous fluid, exuded in abun- 
dance from the glandulous excrescences,® covering the internal surface of the 
® Spallanzani. 
* These glands, or excretory ducts, produce this liquor in great abundance. Spallanzani 
introduced a piece of clean sponge into the crop of a Pigeon, and left it there twelve hours. 
