122 



The Organs of Sense 



moving objects. Many fishes use sensitive structures as a 

 means of exploring the bottom or of feehng their way to their 

 food. The barbel or fleshy filament wherever developed is 

 an organ of touch. In some fishes, barbels are outgrowths 

 from the nostrils. In the catfish the principal barbel grows 

 from the rudimentary maxillary bone. In the homed dace 

 and gudgeon the little barbel is attached to the maxillary. In 

 other fishes barbels grow from the skin of the chin or snout. In 



Fig. 90. — Goat-fish, Pseudxipeneus macxdatus (Bloch). Woods Hole. 



the goatfish and surmullet the two chin barbels are highly 

 specialized. In Poly mixta the chin barbels are modified 

 branchiostegals. In the codfish the single beard is little developed. 

 In the gurnards and related forms the lower rays of the pectoral 

 are separate and barbel-like. Detached rays of this sort are 

 found in the thread-fins (Polyneiindcc), the gurnards {Triglidcc), 

 and in various other fishes. Barbels or fleshy flaps are often 

 developed over the eyes and sometimes on the scales or the 

 fins. 



The structure of the lateral line and its probable relation as 

 a sense-organ is discussed on page 23. It is probable that it is 

 associated with sense of touch, and hearing as well, the internal 

 car fieing ririginally "a modified part of the lateral-Une system," 

 as shfjwn by Parker,* who calls the skin the lateral line and the 

 ear " three generations of sense-organs." 



* See Parker, on the sense of hearing in fishes, American NaturaUst for 

 March, 1903. 



