0456 



Fishes. 



it were going to take in free air, but descends again without reaching 

 the surface of the water." This action would perhaps, in some minds, 

 induce the conclusion that the alteration of course proceeded from 

 the fear of coming in contact with atmospheric air, but the action is so 

 common among fishes, both in aquariums and ponds, that it simply 

 proves that the mud-fish has, in this respect, the normal habits of a fish. 

 The curious position in which the creature is figured in the 'Proceedings 

 of the Zoological Society' 1 had not the good fortune to observe. It 

 seems to be walking on its tendrils, and to be taking an enormous 

 stride with the hind pair : Dr. Gray does not, however, describe this 

 mode of progression. The creature, in the passage I have cited, is 

 described as simply resting on these tendrils at the bottom of the 

 tank, but this resting seems scarcely requisite in a creature whose 

 specific gravity is exactly equal to that of water. It is, however, 

 worthy of observation that this seeming habit of resting on the four 

 extremities is constantly observed in fishes and some even use their 

 extremities for terrestrial progression, a fact noticed by Dr. Gray. 

 There is then no single act, as far as yet observed, of the mud-fish that 

 indicates an amphibian rather than an ichthyac character. The ascer- 

 tained fact of its imbedding itself in clay, and the supposed fact that 

 it passes from river to river by some overland route are equally suscep- 

 tible of parallels among undoubted fishes : of this there are many 

 instances, but I prefer one already cited by Dr. Gray from the 

 * Zoological Journal.' Dr. Hancock observes " When the water is 

 leaving the pools in which they commonly reside ; the yarrow (a 

 species of Esox, Linn.), as well as the round-headed hassar (Callich- 

 thys littoralis) bury themselves in the mud, while all other fishes perish 

 for want of their natural element, or are picked up by rapacious birds. 

 The flat-headed hassar [Doras costata), on the contrary, simultaneously 

 quits the place and marches overland in search of water, travelling for 

 a whole night, as is asserted by the Indians, in search of their object. 

 I have ascertained by trial that they will live many hours out of water, 

 even when exposed to the sun's rays. Their motion overland is 

 described to be somewhat like that of a two-polled lizard : they project 

 themselves forward on their bony arms by the elastic spring of the tail 

 exserted sideways ; their progress is nearly as fast as a man will 

 leisurely walk." 



Again, I would invite those who are familiar with fishes and the 

 more common amphibians to pay particular attention to the habit, so 

 particularly emphasized by Messrs. Bartlett and Hawkins, of dashing 

 or darting through the water : the very expressions indicate the move- 



