32 o THE FLYING FISH. 



" The principal external agents employed in this mode of locomotion are the large 

 lobe of the tail fin and the broad transparent pectoral fins, which, on this occasion, serve 

 at least as a parachute, and which, being situated close to the back, place the centre 

 of suspension higher than the centre of gravity. It is also curious to notice how well 

 the specific gravity of the fish can be regulated, in correspondence with the element 

 through which it may move. The swim-bladder, when perfectly distended, occupies 

 nearly the entire cavity of the abdomen and contains a large quantity of air ; and in 

 addition to this, there is a membrane in the mouth which can be inflated through the 

 gills ; these two reservoirs of air affording good substitutes for the air-cells so freely 

 distributed within the bones of birds, and having the additional advantage of being 

 voluntary in their function. 



The pectoral fins, though so large when expanded, can be folded into an exceedingly 

 slender, neat, and compact form ; but whether they are employed in swimming in the 

 closed or expanded state, I have been unable to determine. 



Under some circumstances of excitement, these fish will leap over the bulwarks of 

 a ship and be killed by the violence with which they strike against the deck or spars. 

 This usually occurs at night, or early in the morning, and a light displayed from the 

 chains of a vessel on a dark night will bring many of them on board in the same 

 manner. Their flesh is the bonne bouche of voyagers ; it bears some resemblance to 

 that of the herring. Although the flying-fish excites so much commiseration for its 

 persecuted state, it is itself predaceous, feeding chiefly on smaller fishes." 



The ancients were well acquainted with the Flying-fish, and in their narratives even 

 improved upon its powers, as was customary with the voyagers of those days, and 

 asserted that as soon as night came on, this fish left the ocean, flew ashore, and slept 

 until morning safe from the attacks of its marine enemies. The generic name of 

 exocaetus, literally a " sleeper-out," refers to this supposed habit. 



THE reader will doubtlessly remember that the power of sustentation in the atmos- 

 phere for a more or less prolonged period is exhibited in the three preceding orders 

 of vertebrated animals, and that, in every case, this object is attained by the modifica- 

 tion of parts already existing, and not by the addition of special members. 



In the bats, for example, the lengthened bones of the fore-limbs, together with the 

 extension of the skin, form a flying apparatus of wonderful perfection, and in the 

 creatures that are popularly, though erroneously, called " flying " squirrels and " flying " 

 rats, the capability of passing through considerable distances, upborne by the air, is 

 achieved by a development of a similar nature but of less extent, the skin of the sides 

 being much widened, though the limbs retain their usual comparative dimensions. 

 These, as well as other creatures who move through the air on the same principle, 

 ought rather to be termed " skimmers." 



In the birds the power of flight is physically owing to the development of the fore- 

 limbs and the modification of the structures which clothe the skin. In the two suc- 

 ceeding orders of vertebrates, no truly flying species are at present known to exist. The 

 only reptile that in this period of the world's history is enabled to sustain itself in the air, 

 even for a limited space, is the little flying dragon, a creature which has its ribs nearly 

 straight instead of curved, and by means of this formation is enabled to sweep from one 

 tree to another just like the flying squirrel. But in the older ages of the world, flying rep- 

 tiles were abundant, with " wings " that measured some thirty feet from tip to tip, and evi- 

 dently both agile and strong of flight like those of the bat, to which they bear a great resem- 

 blance. Lastly, we have several examples among the fishes, where the pectoral fins, an- 

 swering to the fore-limbs of the higher vertebrates, are so greatly expanded and enlarged, 

 that they can be spread horizontally, and bear their owner on a short course through 

 the air. 



In any case, the power of flight is wonderful, but in the fish it seems almost to partake 

 of the miraculous, inasmuch as these creatures inhabit a different element, and do not 

 even breathe the atmosphere into which they are capable of launching themselves. Yet, 

 when more closely examined, the flying power of the fish is not one whit more remark- 

 than able the diving powers of the otter and penguin, both of which creatures are able to 



