64 riSH GALLERY. 



as the opercular spine have a deep double groove in which the 

 'poisonous fluid is lodged, and through which it can be inoculated 

 in the punctured wound. 



The Scicenida (Cases 8, 9) are chiefly coast-fishes of the tropical 

 and subtropical Atlantic and Indian Oceans, frequently entering 

 the mouths of large rivers. Some of the larger species wander far 

 from their original home, and are not rarely found at distant 

 localities as occasional visitors. Thus the "Maigre^' [Scieena 

 aquila) reaches sometimes the British coasts, and has been found 

 at the Cape of Good Hope and on the coast of Southern Australia. 

 Large specimens of allied species {S. antarctica, S. diacanthus) 

 are exhibited in table-cases. To this family also belong the 

 Umbrine {Umbrina) and the "Drum" {Pogonias). The latter 

 derives its name from the extraordinary sounds which it produces. 

 These sounds are better expressed by the word "drumming" than by 

 any other, and are frequently noticed by persons in vessels lying at 

 anchor on the coast of the United States, where these fishes abound. 

 It is still a matter of uncertainty by what means the " Drum " 

 produces the sounds. Some naturalists believe that it is caused 

 by the clapping together of the pharyngeal teeth, which are very 

 large molar teeth. However, if it be true that the sounds are 

 accompanied by a tremulous motion of the vessel, it seems more 

 probable that they are produced -by the fishes beating their tails 

 against the bottom of the vessel in order to get rid of the parasites 

 with which that part of their body is infested. 



Allied to the preceding family' are the Polynemidce (Case 9), 

 characterized by the free filaments which are inserted on the 

 humeral arch at some distance from the pectoral fin, of which, 

 however, they form merely, a detached portion. They can be 

 moved quite independently and are organs of touch. The Polyne- 

 moids are very useful to man ; their flesh is esteemed, and some of 

 the species are provided with an air-bladder which yields a good 

 sort of isinglass ; specimens of this important article of trade are 

 exhibited. These fishes belong to the littoral fauna of the Tropics, 

 and some attain to a length of four feet. 



The family of Sphyr<Bnidte (Case 9 and Table-case) consist of one 

 genus only, Sphyreena, generally called " Barracudas," large vora- 

 cious fishes from the tropical and subtropical seas. They attain to 



