194 REPTILES AND BIRDS. 
feed on vegetables, insects, molluscs, and fishes. They seek the 
coast in the breeding season, where they build their nests on the 
_ sand, in nooks and crannies of the rocks, or on the margin of lakes 
and rivers. 
In the spring the sea-birds assemble in large flocks, pair, and 
proceed to lay; their nests are constructed generally without skill, 
but always lined or carpeted with down, which forms a soft warm 
bed for the embryo progeny. Certain localities are frequented by 
preference, these are occupied by innumerable flocks in the breeding 
season, all of which seem to live together in perfect harmony. Some 
of the families of the Natatores are valuable additions to the poultry- 
yard. Ducks and Geese furnish delicate and nourishing food for 
man; the Swan is gracefully ornamental on our lakes and ponds. 
The down of all the aquatic birds as an article of commerce is of 
immense value in northern countries. Their eggs constitute good 
food, and in many countries the inhabitants consume them in great 
quantities. Nor does their usefulness end here. Guano, so eagerly 
sought for by the farmer, is the excrement of aquatic fowls—this 
has accumulated for ages, until, in the South Pacific Ocean, it has 
formed whole islands, some of them being covered with this valuable 
agricultural assistant to the depth of ninety or a hundred yards. Nor 
is this so marvellous, if it is considered that 25,000 or 30,000 sea- 
birds sleep on these islets night after. night, and that each of them 
will yield half a pound of guano daily, which owes its unrivalled 
fertilising power to the ammoniacal salts, phosphate of lime, and 
fragments of feathers of which it is composed. 
The order of Natatores or Palmipedes we will form into four 
families :—1. Lrevipennes. 2. Lamellirostres. 3. Totipalmates. 
4. Longipennes. 
THE Divers (Brevipeiies). 
Divers, Colymbus; Penguins, Aptenodytes; Auks, Ala, Grebes, 
Podiceps ; and Guillemots, Uvza. 
The Birds which constitute this family of the Natatores are 
characterised by wings so thin and short as to be almost useless for 
the purposes of aérial locomotion. They are also called Lrachyfteres, 
from the Greek compound 6paxis, short, and mrépa, winged. ‘These 
are all habitual divers and indefatigable swimmers, using their wings 
as fish do their fins. ‘To raise these after making the down-stroke 
requires a considerably greater effort than a bird of flight makes in 
raising its wings in the air, for which reason the second pectoral 
