No. 482] 



73 



ically flex the wing for or during the iijHstrokc, and extend it for 

 or during the down. (Pettigrew, 'Animal Locomotion,' Int. 

 Science Series, vol. vii. pp. 122, 182, 1!)4, cVc: IV.M. > 



Marey ('Animal Mechanism,' p. 2();> c^e. : Int. Science Series, 

 1893) equally recognizes the necessity for a diminislied winir-area 

 in the up-stroke, but believes it to be <)l)tained in l)ird> tlnoui^Hi the 

 natural elasticity of the feathers, which enables tliein to return to 

 their ordinary position when the resistance of the air in the down- 

 stroke ceases to raise them. 



The flying-fish's wing, as is known, is formed on quite a different 

 principle from that of a bird or bat. It opens and closes some- 

 what like a fan. A partial automatic closing of this fan at the foot 

 of the downward stroke in flight and opening at the top of the 

 rising stroke would both give the appearance of horizontal vibra- 

 tion when seen either from above or below, and would turn a some- 

 what difficult question of the mechanics of the flight into a very 

 simple one. Indeed we have here flying action on the same general 

 principle as that shown by Pettigrew and Marey to be necessarily 

 provided for in the case of bats and })inls. but the working details 

 of which are different and simpler, as becomes a simj)ler form of 

 wing. 



Perhaps that is the explanation. There must, of course, be 

 some explanation, and that is not only the natural deduction from 

 the peculiar formation of the wing, but it also fits everything in. 



The known (but indistinct) visibility of tlie larger rays of the 

 wings at times diu-ing flight points, perliaps. to a comparative 

 pause with wings full open before hegirning the down -stroke. 

 Such pause would give the open position, and with it the wing- 

 tracery prominence. 



The form of these lishes' wings poiius to this fan-aciion rather 

 than to other known horizontal wing-actions of the nature of that 

 of certain insects — the connnon Hy. for instance : Marey, A-c vif. 

 pp. 204, 206). 



The second quite recent and very important (.bservcr and writer 

 on this subject is convinced of the Hight-action. lie wrii(>s also 

 from personal observation, and is as free from proper mechanical 

 bias as from the improper follow-my-leader habit. One of his 

 remarks, "It is by no means impossible that flying-fish may soar, 



