NERVOUS SYSTEM, SENSES, AND SENSE ORGANS 197 



mud-living form, the barbels are short and are arranged in a 

 transverse row of four across the under side of the shovel-like 

 snout, immediately in front of the protractile mouth (Fig. 450). 

 The related Spoon-bill {Polyodon) has no barbels at all, but the 

 whole of the surface of the peculiar snout has been shown to 

 be highly sensitive, and richly supplied with organs of feeling 

 (Fig. 470). In many oceanic fishes, notably in the members 

 of the tribe of Wide-mouths {Stomiatidae) , a single barbel is 

 developed on the chin, which may be of a most elaborate and 

 sometimes highly fantastic pattern, with a complicated arrange- 



' Fig. 77. BARBELS. 



A. Head of Sciaenid or Drum {Pogonias fasciatus), X ^ ; b. Head of African Cat- 

 fish (Clan'as lazera), X |- ; c. Head of Red Mullet {Mitllus surmuletus), X ^ ; D. 

 Head of Cod (Godus callarias), X ^. 



ment of tassels and other appendages and one or more luminous 

 bulbs of varying size (Fig. 78). In the absence of any data as 

 to the habits of the fishes, it is difficult to understand the exact 

 function of these curious organs. In bottom-living fishes barbels 

 are used to search for food in the sand or mud, but in oceanic 

 forms living in the upper and middle layers of the ocean they 

 obviously cannot be put to such a use. It appears probable 

 that some simple barbels may serve as organs of touch, others 

 may have a sensory function, receiving impressions indicating 

 the approach of other fishes, and others, again, may act as 

 lures. 



In those fishes in which the rays of some of the fins are 



