PRODUCTION OF LIGHT 413 



time they reach the deck of the vessel. The name Ipnops, 

 meaning lantern-face, supposing that the organs are really light- 

 producing, perfectly expresses the remarkable condition of this 

 fish. The Challenger species was called Ipnops murrayi after 

 Sir John Murray, one of the scientific staff on the Challenger at 

 the time of its discovery and editor of the Challenger Reports. 

 In 1 89 1 another species was discovered in the Pacific by the 

 American investigating vessel Albatross under the charge of the 

 eminent American zoologist Alexander Agassiz and named 

 after him ; a single specimen about six inches long was taken 

 from a depth of about 1 360 fathoms off the west coast of South 

 America. 



The Sternoptychid«e are another family in which luminous 

 organs are developed to the highest degree and which have 

 been taken frequently at the surface. Sternoptyx diapliana has 

 been known since the year 1774 when a specimen was described 

 from the West Indies. It was taken by the Challenger all 

 round the v/orld in the tropical seas, in the middle of the 

 Atlantic, in Australian waters, and in the South Pacific. The 

 Challenger records would seem to prove that this species lives 

 at all depths from the surface to 2500 fathoms, but as Doctor 

 Gi'inther says this is very improbable and it is more probably, 

 like Myctophum, not abyssal but pelagic, and only caught in deep- 

 sea dredges or trawls as they ascend towards the surface. Like 

 Myctophum also it comes to the surface at night. It is a small 

 fish with short, deep body, much compressed from side to side. 

 A series of light- organs runs along the lower part of the abdo- 

 men near the ventral edge on each side, another series on each 

 side of the throat in front of the gill-opening, a row of three 

 above and behind the base of the pectoral fins, and another 

 row of three above the anus. On the tail there are two rows 

 of four, anterior and posterior. 



Argyropelecus (silver-axe, from its shape and silvery skin), 

 another member of the same family, is also pelagic with highly 

 developed luminous organs. It has been obtained in the trawl 

 at 500 and 600 fathoms, but is frequently caught at night in 

 the surface net. Giglioli in 1878 obtained over 700 specimens 

 in three days at Messina where the currents and whirlpools 

 bring all kinds of marine forms to the surface. A specimen 

 was taken by the Challenger off Cape Finisterre at 1 125 fathoms, 



