268 
IRIS. 
are near hatching ; at that time the female is frequently fed by the male. 
This is not common to all species, but very conspicuous in the rook, the 
pigeon, and many others. Many species of birds possess a reservoir for 
food, called a craw, or crop ; this seems to answer the same purpose as 
the first stomach in ruminating animals. Here it is the food is softened 
and prepared for the stomach ; from this reservoir it is by some ejected 
for the purpose of feeding their young ; conspicuous in the pigeon. 
The rook has a small pouch under the tongue, in which it carries 
food to its young. It is probable the use of the craw may be extended 
further than is generally imagined; for, besides the common preparation 
of the food to assist its digestion in the stomach, there are some species 
that actually secrete a lacteal substance in the breeding season, which, 
mixing with the half-digested food, is ejected to feed and nourish the 
young. The mammae, from which this milky liquor is produced, are 
situated on each side the upper part of the breast, immediately under 
the craw. In the female turtle dove we have met with these glands 
tumid, with milky secretion, and we believe it common to both sexes of 
the dove genus. The cormorant or pelican genus possess no craw ; but, 
to supply its place, they have a loose skin at the base of the under man- 
dibles, capable of great distention, in which they carry fish to their 
young. The bustard is said to possess a bag of an astonishing size, for 
the purpose of retaining water ; but the most unaccountable and ex- 
traordinary formation in the trachea of many of the males of the duck 
genus, called a labyrinth, is beyond our reach to discover the use of, 
as well as the singular flexure in the windpipe of the hooping swan 
and crane. 
It is much to be wished that naturalists would pay more attention to 
these singular internal formations of birds ; it would no doubt throw 
light on many obscurities in the division of species. The number of 
tail-feathers should also be well ascertained, for this alone is a mark 
of distinction, as in the cormorant and shag. 
INGRIAN FALCON. — A name for the Orange-Legged Hobby. 
INSESSORES (Vigors) — *Perchers, a numerous group of the 
smaller birds.* 
IRIDES.— *The plural of Iris.* 
IRIS. — * The coloured circle of the eye, which in man is blue, 
brown, grey, or hazel. In birds it varies very considerably.* 
