GUKNAEDS. 



479 



Two dorsal fins. Three free pectoral rays. Villiform teeth. 

 Air-bladder generally with lateral muscles, often divided into two 

 lateral halves. The species may be referred to three groups ; — 



1. Palatine teeth none ; scales exceedingly small, except 



those of the lateral line : Trigla. 



2. Palatine teeth none ; scales of moderate size : Lepido- 



trigla. 



3. Palatine teeth present : Prionotus. 



About forty species of "Gurnards" are known from tropical 

 and temperate zones. They are too well known to need 

 detailed description ; one of their principal characteristics is 

 the three free finger-like pectoral appendages, which serve as 



/ ■ 





*x. 



Fig. 214. — Trigla pleuraoanthica. 



organs of locomotion as well as touch, and which are supplied 

 with strong nerves, as noticed above 

 (pp. 108 and 120). The fins are fre- 

 quently beautifully ornamented, espe- 

 cially the inner side of the long and 

 broad pectorals, which is most exposed 

 to the light when the fish is floating 

 on the surface of the water, with pec- 

 torals spread out like wings. The 

 grunting noise made by Gurnards when 

 taken out of the water is caused by 

 the escape of gas from the air- 

 bladder through the open pneumatic duct. Gurnards are 



Fig. 215.— Scute of the 

 lateral line of the same lish. 



