338 ANNUAL EEPOET SMITHSONIAN INSTITUTION, 1933 



plying the clear sea off Santa Catalina Island, where lives in abun- 

 dance one of the giants of the tribe, the California flying fish, which 

 attains a length of about 18 inches. 



THE SURFACE "TAXI" 



On breaking the surface, the huge pectoral fins, the " wings " 

 which function as the upper or anterior pair of planes, are spread 

 wide and taut. This spreading action is apparently too sudden to 

 be caught by the eye. Since these main supporting planes lie well 

 in advance of the fish's center of gravity, the head of the flying fish 

 is supported in the air at a slight angle with the surface of the sea, 

 while the tail droops, because the lower planes (the enlarged pelvic 

 fins), set behind the center of gravity, at first remain folded against 

 the belly. For this reason the elongated and strengthened lower 

 lobe or fork of the caudal fin remains submerged in the water 

 (fig. lb). 



While a few of the flying fishes — such as the primitive, short- 

 winged genus Oxyporhamphus, and the " two-winged " or " mono- 

 plane " type Exocoetus (or Halocypselus) — dart directly from the 

 sea, the typical biplane species normally gain power for their longer 

 flights by a surface "taxi" movement (fig. Ic), to borrow a term 

 from aviation. 



In obtaining the position just described at the surface of the water, 

 the biplane flying fishes may suffer some slackening of their speed. 

 They actually appear almost to balance themselves for a split second 

 at the inception of their surface movements. At least we may be 

 sure that at the start of the taxi sufficient velocity is not yet attained 

 to carry the fish on a very long soar through the air. That this is 

 true was evident from actual observations. When the taxi was mis- 

 governed, much abbreviated, or even eliminated, on account of some 

 condition of wind, wave, or obstacle, the fish was sustained in the 

 air for only a few feet. And when a very short taxi was employed, 

 the first flight was not much longer. 



I believe that I have been able to observe the acceleration in speed 

 which may be assumed to be produced by the taxi. In compound 

 flights it is obvious that the slackened speed at the end of one flight 

 is greatly accelerated by the taxi intervening directly between this 

 soar and the following one. At the end of each taxi the fish appears 

 to be catapulted into the air at a very high speed. What this actual 

 speed is would be very interesting to know. I assume that it is not 

 less than about 55 kilometers (35 miles) per hour, my very rough 

 estimate of the average speed of the whole flights (drawn up from 

 guesses of the distance traversed in timed flights). This estimate 

 is in rough agreement with those of Hankin (1914, 1920), who com- 



