370 ZOOLOGY. 



during a voyage from Sau Francisco to Yokohama, and maintains (1) 

 that he saw them out of water "when the air was ahnost motionless" and 

 that, in fact, " they were not much, if at all less numerous on such occasions 

 than when there was a moderate wind"; (2) that the flapping move- 

 ment is quite regular and very rapid ; and (3) that this movement '■'■may 

 he conthiuecV for the whole or a part of the flight, but is gcneritUij di.scon- 

 tinned after the first few rods, and the course completed by a pure 

 skimming or sailing movement. " It is further claimed that " the course 

 of the flight is generally in a straight or curved line," but is sometimes 

 abruptly changed, " apparently by the aid of the tail," or rather the lower 

 lobe of the caudal fin. The average flight, it is thought, "does not per- 

 haps exceed fifteen seconds, nor extend above four or five hundred feet"; 

 the longest observed "lasted not less than forty seconds, and its extent 

 was undoubtedly over eight hundred feet, and may have exceeded twelve 

 hundre<l feet." 



l*rof. 1). S. Jordan also carefully examined the flight of an Exocoetus 

 {E. californicus) in the waters of Southern California.* He observed it 

 best "in early morning when both air and water were free from motion." 

 " On rising from the water the movements of the tail are continued for 

 some secjonds until the whole body is out of water. While the tail is in 

 motion the pectorals are in a state of very rapid vibration, and the 

 ventrals are folded. When the action of the tail ceases, the pectorals 

 and ventrals are spread, and, as far as we can see, held at rest. When 

 the fish begins to fall, the tail touches the water and the motion of the 

 pectorals recommences, and it is enabled to resume its flight, which it 

 finally finishes by falling in the water with a splash." The flight was 

 thought to sometimes extend to "nearly a quarter of a mile." 



AFFINITIES OF PLEUEACANTHUS.t 



In the Carboniferous and Permian deposits have been found the remains 

 of fishes described under the name of Pleuracanthus, whose afiinities 

 have been involved in considerable doubt. They have been mostly re- 

 ferred to the Selachians, although suggestions have been made that 

 they may belong rather to the Teleosts. The question has lately been 

 reopened by Mr. James W. Davis, and he has come to the conclusion 

 that they claim a nearer relationship to the Teleosts than to the Elasmo- 

 branchs, although there is equal reason to believe that they possess 

 many characteristics in common with the Sharks and Eays, and he 

 is therefore led to place the genus in an intermediate position between 

 the two. The afiinities he thinks are decidedly on the side of the Silu- 

 roids, and it is reasonable, he thinks, to consider them as forerunners of 

 that great group of fishes. 



"It remains," he says, " to be seen what were the successive steps in 



'Jordan (D. S.). Do Flying Fish fly? Am. Nat., vol. siv, pp. 804, 805. 

 t Davis (J. W.). On tlie Teleostcan Affinities of the genus Pleuracanthus. Ann. 

 Mag. Kat. Hist, (5,) vol. v, pp. 349-357. 



