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cular spine, (vide plate 5, jig. 1, b,) from its point to its articu- 

 lation, is three-eighths or half an inch in length in a moderate- 

 sized fish, the posterior two-thirds of which form a flat dagger- 

 like weapon, and the remainder merges into the operculum itself. 

 Its base ends in a concavity, by means of which it is connected 

 to a round prominence of the temporal bone, so as to form a 

 moveable joint admitting of considerable lateral expansion. 

 Normally, the spine is, like the dorsal ones, covered by the 

 tegumentary sheath ; but it is so loose around it that it may be 

 easily unsheathed almost up to its junction with the operculum. 



The fishes should be seen at the time they are caught, or 

 shortly afterwards, in order to observe what formidable crea- 

 tures they are when they have the full use of their weapons. 

 When not annoyed, the fin lies down upon the back of the 

 fish, and is scarcely seen ; but when provoked, they instantly 

 expand the fin, and the pointed opercula are spread out 

 laterally, so as to form an angle of 45 degrees with the sides 

 of the fish. If the hand be the source of vexation, it is almost 

 impossible to escape a wound. I imagine that most wounds 

 are inflicted by the opercular spines, their situation in the 

 expanded state affording greater facility for that purpose. I 

 am also of opinion that the effects of such punctures are more 

 severe than those of the dorsal spines, partly because the 

 fishermen, although they vary in their accounts, generally 

 lavish more abuse upon them, but especially because the 

 organs are larger. 



A question is suggested to our minds, viz. : — Are these 

 weapons useful to ensnare victims for food as well as to repel 

 attacks ? As the fishes are generally seen when on the watch 

 with the fin in the erect state, which is not its passive condi- 

 tion, but the result of muscular activity, we might be led to 

 infer that one of its uses is for employment in the capture of 

 prey; the question, however, can only be answered by observers 

 who may have peculiarly favourable opportunities of watching 

 their habits. 



