98 



ANIMAL LOCOMOTION. 



by the feet during extension and flexion produce, when united 

 in the act of swimming, waved lines, these constituting a 

 chart for the movements of the extremities of swimming birds. 



There is consequently an obvious analogy between the 

 swimming of birds and the walking of man (compare fig. 50, 

 p. 97, with fig. 19, p. 39) ; between the walking of man and 

 the walking of the quadruped (compare figs. 18 and 19, pp. 

 37 and 39) ; between the walking of the quadruped and the 

 swimming of the walrus, sea-bear, and seal; between the 

 swimming of the seal, whale, dugong, manatee, and porpoise, 

 and that of the fish (compare fig. 32, p. 68, with figs. 18 and 

 19, pp. 37 and 39); and between the swimming of the fish 

 and the flying of the insect, bat, and bird (compare all the 

 foregoing figures with figs. 71, 73, and 81, pp. 144 and 157). 



Flight of the Flying -fish ; the kite-like action of the Wings, etc.— 

 Whether the flying-fish uses its greatly expanded pectoral fins 



Fig. 51. — The Flying-fish (Exocoetus exsiliens. Linn.), with wings expanded and 

 elevated in the act of flight (vide arrows) This anomalous and interesting 

 creature is adapted both for swimming and flying. The swimming-tail is 

 consev|uently retained, and the pectoral fins, which act as wings, are 

 enormously increased in size. — Original. 



as a bird its wings, or only as parachutes, has not, so far as I 

 am aware, been determined by actual observation. Most ob- 

 servers are of opinion that these singular creatures glide up 

 the wind, and do not beat it after the manner of birds ; so 

 that their flight (or rather leap) is indicated by the arc of a 

 circle, the sea supplying the chord. I have carefully examined 

 the structure, relations, and action of those fins, and am satis- 

 fied in my own mind that they act as true pinions within 



