308 FLYINQ REPTILES, FISHES, AND MOLLUSCS. 



They have long been famous for their powers of 

 leaving the water; and, indeed, the generic name, 

 Exocoetus, which is formed from two Greek words, 

 signifying sleeping out, was given to these fishes by 

 the earlier naturalists, because they believed that the 

 Flying Fishes left the sea at night, and went on shore 

 to sleep. 



In all these fishes, the pectoral fins are enormously 

 developed, so that when they are extended they look 

 exactly like wings, and perform very similar functions. 

 Whether urged by fear, as some persons think, or by 

 sport, as others think, these fishes are in the habit of 

 springing out of the water, and of being upborne by 

 their wing-like fins in the air. 



The mode in which this feat is achieved is identical 

 in principle with that which enables the air trespassers 

 which we have already noted to support themselves in 

 their aerial journeys. Just as in the Fljing Colugo, 

 the Flying Squirrels, the Flying Marsupials, the 

 Flying Dragons, and the Flying Frogs, the membranes 

 bv which they support themselves in the air are folded 

 closely to the body while the creatures do not require 

 to use them, so in the Flying Fishes the great pectoral 

 fins are folded into a very neat and compact form 

 v hile the fish is swimming, and do not interfere in the 

 least with their owner's progress through the water. 

 Whether or not they are used in swimming is a 

 doubtful point, but in all probability they can be used 

 in guiding the course and balancing the body, just as 

 if they had been no larger than those of ordinary 

 fish. In some species the ventral fins are also very 

 large, so that the creature appears to have four wings. 



