The black fishes, which swim in the cool mid-water layers of the ocean, are full of life 

 and activity. Numerous shoals, like those of herrings or sardines, move around in compact 

 groups, lit by countless phosphorescent organs, such as myctophids or scopelids (lantern- 

 fishes). Their agility is no protection against fierce predators — such as Alepisaurus ferox, 

 a fish that may reach more than a yard in length. Running along the back is a high, many- 

 rayed, dorsal fin like those of tropical sail-fishes. Being without light organs it swims and lurks 

 under the cover of darkness, and taking advantage of the light emitted by these schools of 

 harmless fishes, it wages a fearful slaughter. 



The eel-like Sacco pharynx fishes are no less dangerous. Two small close-set eyes, like 

 those of moray eels, overlook a formidable mouth with its slanting gape. When their stomachs 

 are empty the undulations of their slim, pliant bodies light up a row of luminous points, but 

 when they have swallowed some large-sized prey the stomach becomes enormously distended 

 and only returns to its original shape after a laborious digestion. These fearsome animals can 

 exceed a length of 6 feet. Like other eels they metamorphose from a leptocephalous type of 

 larva which is characterised, as soon as it is hatched, by a marked development of the lower jaw. 

 The smaller stomiatoids with formidable teeth prey on other mid-water, deep-sea fishes. The 

 hatchet-fishes (Argyropelccus hemigymnus) which are only an inch or so long, are their chosen 

 victims. These are strange-looking fishes with a large head measuring nearly half the length 

 of a body provided with two large tubular eyes. Their metallic-looking flanks are set with 

 light-organs which reveal their grotesque shape. Another form, Opislhoprodus grimaldii, has 

 two tubular eyes looking vertically upwards from a luminous head. 



The mid-water, deep-sea fauna has now been well studied, naturalists on great scientific 

 cruises having collected many kinds of black fishes. The general public was keenly interested 



A ceratioid angler-fish (Linophryne arborifera) ( X 2). 



A hatchet-fish ( Argyropelecus hemigymnus) ( X 2). 



when these fishes were on view in the International Exhibitions of 1867 and 1878 in London and 

 Paris held after the " Challenger ", " Travailleur " and " Talisman " Expeditions, and every 

 visitor to the Oceanographic Museum at Monaco knows of the collections made by Prince 

 Albert L 



The deep-sea angler-fishes (ceratioids) attract a good deal of attention, which is not sur- 

 prising in view of their extraordinary appearance. Descending from bottom-living angler- 

 fishes, they have kept the fishing-line but this has become highly modified. It is frequently 

 very long and ends in a spherical bulb bearing aluminous gland. Sometimes it branches into a 

 bunch of phosphorescent tentacles. In species like Linophryne this intriguing arrangement is 

 coupled with a many-branched barbel like a seaweed glowing in the darkness. The body is 

 more or less globular in form, the pelvic fins have disappeared and the skin is raised into papillae 



178 



Antarctic nototheniid fishes. Photograph by Dr. Sapin- 



Jaloustre. 



The coelacanth (Latimeria chalumnae). Photograph 



by J. Miliot. 



