The manta was encountered seven or more times. 

 The northernmost record was on Dec . 1^, about 

 60 miles W of Punta San Juanico, Baja 

 California (surface water less than 23°C). 



The southernmost was in the shore waters of 

 Cocos Island, where two followed or kept in 

 close touch with the skiff for fully half an 

 hour . These approached within oar ' s length 

 and the larger was at least km. in breadth 

 (surface water 26.1*°C). The dorsal aspect of 

 their upcurled fin-tips, as seen in the air, 

 was blackish, but as soon as they submerged a 

 meter or more the color reflected through the 

 water became a pale tan, extraordinarily 

 reducing visibility. 



Coryphaena hippurus . Dolphin: dorado. 

 Commonly encountered nearly everywhere S of 

 15°30' N, where on Dec. 13 the surface 

 temperature was below 23°C. Numerous dolphins 

 were captured. Their stomachs contained squids, 

 flying fishes, and parasitic nematodes. 



The largest example measured 150 cm. in 

 standard length and was taken at 09° l6' N, 

 89°l8' W, on Nov. 20 (surface water 25.3°C). 

 The position is in the "Dome" area, 200 miles 

 W of Costa Rica. With this and with two other 

 dolphins I confirmed observations made by 

 Benjamin Franklin in the Atlantic Ocean on 

 Sept. 2, 1726. 



Franklin's account, which is unknown to most 

 ichthyologists, relates to his first return 

 from England to Philadelphia. His Journal 

 states: 



"We caught a couple of dolphins and fried them 

 for dinner... These fish make a glorious 

 appearance in the water; their bodies are of 

 a bright green, mixed with a silver colour, 

 and their tails of a shining golden yellow; 

 but all this vanishes presently after they are 

 taken out of their element, and they change 

 all over to a light grey. I observed that, 

 cutting off pieces of a just-caught, living 

 dolphin for bait, those pieces did not lose 

 their lustre and fine colours when the 

 dolphin died, but retained them perfectly." 



The repetition of this experiment showed that 

 skin overlying severed chunks of myomeres 

 from the back remained dark blue after the 

 same area on the dying fish had turned almost 



white. In like manner, sections from the 

 belly retained their pristine silvery yellow 

 hue, with pale blue spots, after the same part 

 on the body of the fish had faded. 



The dermal chromatophores are under combined 

 control of hormones and the parasympathetic 

 nervous system. Proximal severing of the 

 fibers evidently leaves the hormonal influence 

 unopposed. 



Exococoetidae. Flying fish. Observed 

 throughout the cruise. An example of 

 Cypselurus calif ornlcus flew aboard Stranger 

 during the night of Nov. 7 at 30°3U'N, not far 

 from San Diego, and another, kO cm. in 

 standard length, on Dec . 15, just N of Cedros 

 Island, Baja California. The surface water 

 at the first of these localities was 19.1°C. 



Flying fish were conspicuous above the bank 

 surrounding the Alijos Rocks, Nov. 95 off the 

 Gulf of Tehuantepec, Nov. 16; and at 09° 1+6' N, 

 93°30' W, 300 miles from the continent, 

 Dec. 6. Weather had much to do with 

 observation because the fishes emerged most 

 actively during strong winds. 



An example of Cypselurus nigricans , l8 cm. in 

 standard length, flew aboard within sight of 

 the Gulf of Dulce, Panama, on Nov. 25 (surface 

 water 26. VC). 



REPTILES 



Pelamis platurus . Sea snake. The northern- 

 most specimen was taken under a light in the 

 evening of Nov. 15, at about lk° N, 96 <, 10' W. 

 This was in a zone of upwelling to leeward of 

 the Gulf of Tehuantepec. The surface 

 temperature was only 25°C, whereas a few hours 

 earlier and to the north it had been 29°C . 

 Another was captured Dec . 1 in the Gulf of 

 Panama (surface water 27°C). 



Sea snakes were most conspicuous off western 



Panama, near Coiba Island, on Nov. 25, as 



many as ten at once sometimes being within sight 



The distribution of this 6pecies, the only 

 sea snake along the Pacific coast of America, 

 is graphically correlated with the major 

 oceanic circulation. The normal range extends 

 from no more than latitude 02°S (or even 

 nearer the equator, at La Plata Island, 



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