CHAP. IV. LEAPING OF FISHES. 113 



shape of the wings in the humming-birds ; and they 

 also possess a degree of rigidity, from the rays being 

 close together, which is very unusual in other tribes. 

 Now, the effects of this peculiar sort of fin are very re- 

 markable: they are analogous to the wings of birds; 

 and give to the tunny, and the different bonitos, a 

 speed which is almost incredible. We have often 

 watched them in the Pacific, from the sides of a vessel 

 which was going at the rate of ten miles an hour ; and 

 yet, notwithstanding this speed, the bonitos would play 

 round it as if it was immoveable. One moment, they 

 would be at the stern ; while the next, with a few pro- 

 digious darts, they might be seen playing round the 

 head, as if in mockery of the slowness of the vessel, 

 and rejoicing in their own superiority. The great size 

 of the pectoral fin in the gurnards (Triglidce), as it has 

 been supposed, is for the purpose of supporting their 

 large heads, they being what are called ground fish. 

 or swimming very near the bottom of the sea ; but this, 

 we think, is very questionable. 



(133.) Many fishes can leap above the surface of the 

 vyater ; and among these, perhaps, the salmon {fig. 31.) 



is most conspicuous, or, at least, the best indigenous ex- 

 ample. Although usually inhabiting the ocean, they 

 advance up the rivers at certain seasons of the year (in 

 common with many others), for the purpose of de- 

 positing their spawn ; if, on these occasions, they find 

 themselves opposed by any unexpected obstacle, they 

 overcome it by taking the most astonishing leaps. Thus, 

 on the river Liffey, in Ireland, there is a cataract about 

 nineteen feet in height: over this the fish will fre- 

 i 



