PHOSPHORESCENCE OF THE SEA. I3] 
the passage from Cumana to Caraccas, so great is 
the skill of the Guayqueria pilots. They descend- 
ed the Manzanares with rapidity, delighted with the 
sight of its marginal cocoa-trees, and the glitter of 
the thorny bushes covered with noctilucous insects, 
and left with regret a country in which every 
thing had appeared new and marvellous. Pass- 
ing at high water the bar of the river, they entered 
the Gulf of Cariaco, the surface of which was gently 
rippled by the evening breeze. In a short time the 
coasts were recognised only by the scattered lights 
of the Indian fishermen. 
As they advanced toward the shoal that s surrounds 
Cape Arenas, stretching as far as the petroleum 
' springs of Maniquarez, they enjoyed one of those 
beautiful sights which the phosphorescence of the 
sea so often displays in tropical climates. When the 
porpoises, which followed the boat in bands of fifteen 
or sixteen, struck the surface of the water with their 
tails, they produced a brilliant light resembling 
flames. Each troop left behind it a luminous track ; 
and as few sparks were caused by the motion of an 
oar or of the boat, Humboldt conjectured that the 
vivid glow produced by these cetaceous animals was 
owing not to the stroke of their tails alone, but also 
to the gelatinous matter which envelops their bo- . 
dies, and which is detached by the waves. 
At midnight they found themselves among some 
rocky islets, rising in the form of bastions, and con- 
stituting the group of the Caraccas and Chimanas. 
Many of these eminences are visible from Cumana, 
and present the most singular appearances under 
the effect of mirage. Their height, which is pro- 
bably not more than 960 feet, seemed much greater 
