618 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
also the deeper zonary regions. For in the tropical zone there are 
numerous nyctipelagic organisms, which by day shun the glow of the 
perpendicular rays of the sun and betake themselves into the cooler, 
more or less deep layers of water; but at night these bathypelagie ani- 
mals and plants appear at the surface in such immense crowds that 
they are not surpassed in quantity by the “immeasurable swarms” of 
pelagic organisms in the temperate and cold zones. 
During my trip through the tropical region of the Indian Ocean, as 
well on the way to Ceylon (from Bombay) as on the return (from Soco- 
tora), I daily wondered at the great richness of pelagic life on the mir- 
rored surface. At night the “‘whole ocean, as far as the eye could see, 
was a continuous shimmering sea of light” (25, p. 52). The luminous 
water, which at night we scooped up directly from the surface with 
buckets, showed a confused mass of nyctipelagic luminous animals (Os- 
tracods, Salpa, Pyrosoma, Medusa, Pyrocyste), so closely packed that 
in a dark night we could plainly read the print in a book by the bright- 
ness of their pelagic light.. The crowded mass of individuals was not less 
considerable than I have so often found in the Mediterranean in the 
currents of Messina. What quantities of food the plankton must here 
furnish to the larger animals was shown by the vast schools of great 
meduse and flying-fish, which for days accompanied our vessel; and 
this mass covered large areas of the open Indian Ocean, midway 
between Aden and Ceylon. Just such plankton masses I have received 
through the kindness of Capt. Rabbe from other tropical parts of the 
Indian Ocean, between Madagascar and the Cocos Islands, and be- 
tween these and the Sunda Archipelago. I encountered a wonderfully 
rich and thick planktonic mass in a pelagic current of the southwest 
monsoon drift, 50 nautical miles south of Dondra Head, the southern 
point of Ceylon.* Ihave referred to the richness of this in my “Indian 
Journal” (25, p. 275). 
That the tropical zone of the Atlantic Ocean also possesses a vast 
wealth of plankton is shown by many older accounts, but especially 
from the experience of the Challenger. In the middie of the Atiantie, 
between Cape Verde and Brazil, Murray observed colossal masses of 
pelagic animals; and if by day they were scarce at the surface, he con- 
tinually found them below the surface, in depths of 50 to 100 fathoms 
and more (6, pp. 195, 218, 276, ete.); at night they ascended to the sur- 
face and filled the sea far and wide with a brilliant glow (pp. 170, 195, 
etc.). ‘On the whole cruise along the Guinea and equatorial currents, the 
pelagic life was exeeedingly rich and varied, in the quantities of individ- 
uals as well as of species, much more than anywhere else in the northern 
or southern part of the Atlantic Ocean. The greatest quantities were 
seen in the Guinea current during calins, when the sea literally swarmed 
“A part of the new species of pelagic animals which I found in this astonishingly 
rich oceanic current are described in my ‘ Reports on the Siphonophora and Radio- 
laria of H. M. 8. Challenger.” 
“ 
