2810 



THE BONY FISHES AND GANOIDS 



Snakefishes 



Parasitic Fish 



cave fish are closely allied to certain small fishes from the tropical Atlantic and 

 Indian Oceans forming the genus Brotula, and characterized by the elongate body 

 being covered with minute scales, the moderate-sized eyes, the reduction of 

 each pelvic fin to a single filament, of which the extremity may by split, the 

 villiform teeth, and the presence of barbels on the muzzle; these barbels being 

 reduced in the cave fish to small tubercles. With the exception of these cave 

 fish, all the members of this family are marine forms; and it is very curious that 

 among the latter there are two very rare species, respectively constituting the 

 genera Typhlonus and Aphyonus, found at great depths in the southern oceans, 

 which are are also completely blind, and apparently unprovided with any phos- 

 phorescent organs. 



The typical genus Ophidium, constituting, with an allied form, the 

 second subfamily, has the pelvic fins replaced by a pair of barbel-like 

 filaments; the elongated and compressed body being covered with very minute 

 scales, while the eyes are medium, and the teeth small. The few species of this 

 genus range over the Atlantic and Pacific. In the South American, South African, 

 and Australasian seas there occur three much larger but nearly allied fishes, which 

 have been referred to a second genus ( Genypterus) , on account of the outer row of 

 teeth in the jaws, as well as those of the single palatine series, containing some 

 enlarged tusks. These fish are of considerable commercial importance, and are 

 known at the Cape as klipvisch, and in New Zealand as Cloudy bay cod, or ling. 



Some half-score species of very small eel-like fishes, scientifically 

 known as Fierasfer and Encheliophis, and inhabiting the Mediter- 

 ranean, Atlantic, and Indo-Pacific, have an especial interest on account of their 



curious mode of life. They 

 constitute a subfamily, 

 readily characterized by the 

 total absence of pelvic fins 

 and by the vent being situ- 

 ated at the throat; and are 

 parasitic in other marine 

 animals, frequenting the 

 hollows in the bodies of jelly- 

 fish, the breathing chambers 

 of starfishes and sea cucum- 

 bers, and sometimes insinu- 

 ating themselves between the 

 layers of the mantle of pearl 

 mussels or other bivalve 

 mollusks. Occasionally they 

 may become embedded in the substance of the shell of the pearl mussel by the 

 deposition of pearly matter over their bodies; an instance of this peculiar mode of 

 preservation being shown in the accompanying illustration. 



The third subfamily is represented by the well-known sand eels or launces of 

 which a British species (Amnwdytes tobianus} is figured in the illustration so 



PARASITIC FISH EMBEDDED IN A PEARL MUSSEL. 

 (From Gtinther, Proc. Zool. Soc., 1886.) 



