CHONDEOPTERTaiANS. 415 



sides with suitable food, and finding at different depths 

 the temperatiire most congenial to their health and com- 

 fort, whether at the torrid or frozen zone. Some of the 

 scaly tribe, to whom fresh water is not less palatable 

 than salt or brackish, may even go far inland, visit with- 

 out a ' Guide ' lakes hitherto undescribed by tourists, or 

 follow, Jl la Bruce, the meanderings of some mighty 

 river from its mouth up to its sources. Supported in a 

 fluid of nearly the same specific gravity as their own, the 

 upper portion of the body throws no . weight upon the 

 lower, and weariness is impossible. "Where there is no 

 fatigue, repose becomes unnecessary ; and accordingly we 

 find these denizens of the deep, like their ' mobile mo- 

 ther,^ the sea, ' who roUs, and rolls, and rolls, and still 

 goes rolling on,' never perfectly at rest. When the day 

 has been passed in swimming, and the evening paddled 

 out in sport, away float these everlasting voyagers through 

 the night, and are borne in a luxurious hydrostatic bed, 

 wherever the current chances to carry them ; and, with 

 no other trouble than that of occasionally opening their 

 mouths for a gulp of fresh air, on they go, till early 

 dawn, bursting upon a pair of unprotected eyeballs, 

 gives their owners timely notice to descend deeper, and 

 to strike out with fins and tail in whatever direction 

 waking thoughts may suggest. To such tourists Ma- 

 dame de Stael's definition of travel, 'le voyage, un 

 triste plaisir,' cannot of course apply. Their whole jour- 

 ney indeed through life is singularly placid, conducive 

 not only to health, but also to extreme longevity ; for 

 though it be not true, as af&rme^ by Aristotle, that fish 

 have no diseases or ' plagues,' it is nevertheless certain 

 that large fish, well supplied with little ones for food, and 

 so armed as to be capable of defending themselves against 

 violence, will live several centuries — a longevity to which 

 immunity from the risks of sudden changes of tempera- 

 ture, a secured sufficiency of wholesome diet, and their 



