{ | ‘5 
NATATORES. © 183 
toe is fully developed, and is placed on the same level 
as the other toes. It would be’ highly interesting to 
elucidate other peculiarities of the grallatorial groups, by 
eomparing them, in the above manner, with other circles ; 
but this cannot, on the present occasion, be done, and 
we must now pass onward to the succeeding order. 
CHAP. XIV. 
ON THE ORDER OF NATATORES, OR SWIMMING BIRDS. 
 (204.) Tue last ereat. division of the ornithological 
circle is composed of such families as habitually live 
upon the waters, and are hence called Natatorial. 7 
_ Their feet, which are almost always very short in pro- 
portion to the bulk of the body, are generally placed 
far behind the equilibrium, and are thus especially 
adapted for swimming: the toes are rather long, and 
are more or less united by a thin, firm, expansile 
membrane, or web: the feet may thus be com- 
pared to broad oars or- paddles, which oppose a 
considerable resistance to the water, and enable these 
birds to swim and dive with the greatest facility. 
They are the only order, except the waders, which 
have the neck very considerably longer than the legs, 
—a beautiful provision of nature, since they are thus 
unabled to seize their food considerably above or 
beneath the equal level of the element they live upon. 
The structure of the plumage is particularly adapted 
to resist wet: its outer surface is close, compact, 
smooth, and somewhat oily; beneath this there is a 
second series of feathers, of a soft and downy texture, 
_ which is not only impenetrable to water, but calculated 
at the same time to keep the body in a constant and 
equal state of warmth, and thus to guard the bird from 
_ those injurious effects resulting from sudden trans- 
: nN 4 
