98 LOCOMOTION OF PISHES. 



backs, this power seems to belong to the greater 

 number of fishes ; and to be exercised sometimes in 

 sport, at others to avoid their enemies, to reach 

 their prey, to escape from confinement, or to over- 

 come obstacles during their migrations. Thus the 

 haddock, when pursued by the dog-fish, or other 

 voracious fishes, is observed frequently to leap for 

 an instant out of the water ; and it is, as pressed 

 by the pursuit of their numerous enemies, that the 

 various kinds of flying- fishes — of which we shall 

 speak more fully presently, as not rising into the 

 air, but of maintaining for some time a continuous 

 course therein — spring out of their natural element. 

 Many fishes, also, which feed on insects fluttering 

 over their heads, are enabled to reach them only by 

 these means ; and the rising of the trout out of its 

 stream, for this purpose, is well known to anglers. 

 The silvery trichiurus, a taper-shaped fish, inhabit- 

 ing the lakes of South America, India, and China, 

 not unfrequently takes such surprising somersets 

 after its prey, as to fall into vessels which are acci- 

 dentally passing at the time. Other fishes, again, 

 as the mullets and the carp, are observed frequently 

 to escape in this way from the nets by which they 

 have been environed, a whole shoal of them some- 

 times vaulting over, one after another, Hke a flock 

 of sheep over a fence. This circumstance, "with 

 respect at least to the former, was known to 

 Oppian — 



The mullet, wlien encircling seme's enclose, 

 The fntaJ threads and treacherous bosom knows; 



