SWIMMING BIRDS. 
269 
from the water^ as well as supplies some of them with a soft 
material for their nests. In addition to the natural polish 
of the plumage, the feathers are lubricated with an oily se- 
cretion, so that water does not penetrate them. 
The late Professor Macgillivray divided the swimming 
birds into four smaller orders, which he named and charac- 
terized from their different modes of taking their food. 
The Geese and Ducks he called Crihratores, or Sifters, from 
the food being sifted through the lamellated edges of the 
beak ; his order UrinatoreSj or Divers, contained those birds 
which obtain the greater part of their food by diving, such 
as the Grebes, Divers, Auks, and Guillemots; his order 
Mersatores, or Plungers, contains the long- winged species 
which can keep up a sustained flight, like the Gannets, 
Gulls, and Terns ; while the Jagers, or Skuas, the pirates of 
the aquatic order, are placed by him in a section which, 
from their habits, he calls S^oliatores. 
We cannot refrain from quoting a passage from Mr. 
Hewitson^s work, to the accuracy of which we were our- 
selves witnesses in 1851, when visiting the lofty cliffs of 
Noss. Some of the birds mentioned had disappeared, but 
from the myriads of sea-birds still on the rocks, there seemed 
as if there was no vacancy for other birds. 
