FLYING-FISH. 57 
in general separate with great facility after the pe- 
riod of fructification. | 
Beyond 22° of latitude they found the surface of 
the sea covered with flying-fish (Exocetus voliians), 
which sprung into the air to a height of twelve, fifteen, 
and even eighteen feet, and sometimes fell on the deck. 
The great size of the swimming-biadder in these 
animals, being two-thirds the length of their body, 
as well as that of the pectoral fins, enable them to 
traverse in the air a space of twenty-four feet hori- 
zontal distance before falling again into the water. 
They are incessantly pursued by dolphins while un- 
der the surface, and when flying are attacked by 
frigate-birds and other predatory species. Yet it 
does not seem that they leap into the atmosphere 
merely to avoid their enemies; for, like swallows, 
they move by thousands in a right line, and always 
im a direction opposite to that of the waves. The 
air contained in the swimming-bladder had been 
supposed to be pure oxygen ; but Humboldt found it 
to consist of ninety-four parts of azote, four of oxy- 
gen, and two of carbonic acid. 
On the Ist July they met with the wreck of a 
vessel, and on the 3d and 4th crossed that part of the 
ocean where the charts indicate the bank of the Maal- 
Stroom, which, however, is of very doubtful existence. 
As they approached this imaginary whirlpool they 
observed no other motion in the waters than that 
produced by a current bearing to the north-west. 
From the time when they entered the torrid zone 
(the 27th June) they never ceased to admire the 
nocturnal beauty of the southern sky, which gradu- 
ally disclosed new constellations to their view. “One 
experiences an indescribable sensation,” says Hum- 
