GUN LOCK ACTION OF FIN RAY. 



89 



with numerous small projections, wliicli give it arougli, 

 denticulated appearance. The term Balistes refers to 

 another peculiarity in the structure of this and the 

 second spine. The hones or rays of the first dorsal 



FILE-FISH {Balitites capriscns). 



fin are so contrived as to act in concert, with con- 

 siderable force, in suddenly elevating the fin at the 

 pleasure of the animal. Though the foremost or largest 

 be pressed ever so hard, it will not stir; but if the 

 last or smallest ray of all be pressed but very slightly, 

 the other two immediately fall down with it, as a 

 cross-bow is let off by pulling down the trigger. For 

 this reason the fish is called at Eome ^^ pesce balcstra,'' 

 the latter name having been used by the Romans for an 

 engine of war, constructed on a somewhat similar 

 principle, for throwing dar's and arrows. I have 

 shown this wonderful structure to my friend Mr. W. E. 

 Pape, the well-known gun and rifle maker of Newcastle- 

 on-Tyne. He was much struck with (I was going to 

 write) the iugenuity of its conformation, and has promised 

 he will see if he cannot adopt its principle for some of 

 his safety rifle locks. 



