194 ON THE CLASSIFICATION OP BIRDS. 
tudes, and not only fly well, but swim and dive 
with great swiftness. The provident Chinese avail 
themselves of these birds, which they train to catch 
fish, a ring being put round the neck to prevent the 
game being swallowed : the common cormorant is a 
perfect example of this group. The gannet is the 
only Jlritish bird of the genus Dysporus, although 
several others have been discovered : they seem to be 
general wanderers over the whole world, and is that 
particular race which the frigate pelicans select more 
than any other as objects of attack and plunder. The 
history of the frigate pelicans, no less than their whole 
structure, is highly interesting : they are truly rapa- 
cious birds, endowed with a sight remarkably piercing, 
with an immense expanse and power of wing, and with 
the most determined audacity ; they attack other birds 
nearly of their own size, forcing them to disgorge or 
relinquish the fish they may have caught. ITe know 
not a more imposing sight than half a dozen of these 
aerial birds soaring in mid-air, and suddenly falling 
down into the sea upon a shoal of fish that have ap- 
proached too near the surface. At other times, during 
a storm, they soar to such a height, that, notwithstand- 
ing their size, they appear but as specks in the firma- 
ment : all their powers of motion, in fact, are concen- 
trated in the wings; for the feet are so short and 
imbecile, that when upon the ground they may be 
approached with perfect ease. These birds, although 
common in the tropical seas, are not found beyond, 
and are thought to belong but to one species. The 
same regions, as their name implies, are inhabited by 
the tropic-birds (Plurton), whose flight, although in- 
ferior, is frequently as high as that of the frigate-bird : 
there are but two species, both having two of the tail 
feathers very long. The darters (Plotus) terminate 
this family : they are distinguished from all the pre- 
ceding by the excessive length and slenderness of the 
neck, which seems like the body of a serpent united 
to that of a cormorant ; the bill is very sharp ; and this. 
