IX. 
THE PELAGIC FAUNA AND FLORA. 
Tur pelagic fauna is made up of very distinct factors. It 
contains many animals which pass their whole life as wanderers 
probably within a couple of hundred 
on or near the surface, 
fathoms, — where they drift helplessly at the mercy of the 
winds and waves and eurrents. While there are stretches 
of the sea along the line of currents, as, for instance, the 
course of the Gulf Stream, where the pelagic fauna is more 
abundant than in other marine regions, there seems to be 
no portion of the sea from which it is totally absent. The 
pelagic fauna proper includes representatives of all classes of 
the animal kingdom, though usually these are of smaller size 
than their allies on or near the continental shores and beaches. 
The majority of them are noted for the greater or less trans- 
pareney of their bodies, while their coloring is generally har- 
monious with that of the surrounding sea. Pale, bluish, and 
translucent colors characterize the majority of the pelagic ani- 
mals that live during the day upon the surface of the water. 
Such are, for instance, the violet or blue tints of the transpar- 
ent acalephs and siphonophores ; those of the Janthina, which 
its name describes, of the glassy heteropods and pteropods, and 
of the iridescent ctenophores, which seem, when touched by the 
sun, like rainbow fragments floating in the water. 
The brilliant Sapphirina, the red Daphnia and elobigerina, 
the pinkish or bluish Salpa, are often seen in such masses that 
they discolor the water for miles, and make the ocean like a sea 
of milk. By daylight, only the practised eye detects the sep- 
arate forms which, from their number and delicate texture, melt 
into each other. But at night the scene changes. The greater 
number of the pelagic animals are brilliantly phosphorescent ; 
