618 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



also the deeper zonary regions. For in tlie tropical zone tliere are 

 numerous nyctipelagic organisms, whicli by day sliun the glow of the 

 I)erpendicular rays of the sun and betake themselves into the cooler, 

 more or less deep layers of water; but at night these bathypelagic ani- 

 mals and plants jippear at the surface in such immense crowds tliat 

 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 ''Avhole 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 {On- 

 tracods, tSaljia, Pyrosoma, Medusw, Fyrocystcc), 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 aniuials was shown by the vast schools of great 

 medusre 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 i>lanktou masses I have received 

 through the kindness of Capt. llabbe 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 iielagic current of the southwest 

 monsoon drift, 50 nautical miles south of Dondra Head, the southern 

 point of Ceylon.* I have 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 middle of the Atlantic, 

 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 (0, pp. 195, 218, 27G, etc.); at night they ascended to the sur- 

 face and filled the sea far and wide with a brilliant glow (pp. 170, 105, 

 etc.). '' On the ichole cruise along the Guinea and equatorial currents, the 

 pelagic life teas exceedingly rich and varied, in the quantities of individ- 

 uals as well as of vspecies, onueh more than anywhere else in the northern 

 or soutliern part of the Atlantic Ocean. The greatest quantities were 

 seen in the Guinea current during calms, when the sea literally sicarmed 



*A part of the new species of pelagic animals wliich I found in this astonishingly 

 rich oceanic current arc described in my '■ Keports on the Siphonophora and Kadio- 

 laria of H. M. S. Challenger." 



