FEELERS AND ANTENNA 37 



lined with a dark or, more usually, a black epithelium. 

 The mouth, pharynx, and respiratory channels, and 

 even the visceral cavity, of Bathysaurus and Ipnops, 

 and indeed of all really deep-sea fishes, are black. 

 It can be of no use to any animal to be black 

 inside; and the only explanation hitherto given is 

 that the deposit of pigment is the expression of some 

 modification in the excretory processes of the abysmal 

 fishes. 



It was mentioned above that the absence of eyes is 

 to some extent compensated by the great extension of 

 feelers and antennae. Many of the jelly-fishes have 

 long free tentacles radiating in all directions ; the rays 

 of the ophiuroids are prolonged ; the arms of the 

 cuttle-fish are capable of enormous extension. The 

 antennae of the Crustacea stretch widely through the 

 water, and, in Aristoeopsis, cover a radius of about 

 five times the body-length. In Nematocarcinus the 

 walking-legs are elongated to almost the same extent ; 

 and this crustacean steps over the sea-bottom with 

 all the delicacy of Agag. The curious arachnid-like 

 pycnogonids have similarly elongated legs, and move 

 about, like the ' harvestmen ' or the ' daddy-long-legs/ 

 with each foot stretched far from the body, acting as 

 a kind of outpost. The fishes, too, show extraor- 

 dinary outgrowths of this kind. The snout may be 

 elongated till the jaws have the proportions of a pair 

 of scissor-blades, each armed with rows of terrible 

 teeth ; or long barbels, growing out from around the 

 mouth, sway to and fro in the surrounding water. In 

 other cases the fins are drawn out into long streamers. 

 All these eccentricities give the deep-sea fishes a 

 bizarre appearance ; their purpose is plainly to act as 

 sensory outposts, warning their possessor of the pre- 

 sence of enemies or of the vicinity of food. 



All deep-sea animals are of necessity carnivorous, 

 and probably many of them suffer from an abiding 



