254 EDGE OF THE JUNGLE 
great, grinning catfish rose, and slowly sank, 
leaving outlines discernible in ripples and bub- 
bles with almost Cheshire persistency. One of 
my Indians, passing in his dugout, smiled at my 
peering down after the fish, and murmured, 
“Boom-boom.” 
Then came a day when one of these huge, ami- 
able, living smiles blundered into our net, a smile 
a foot wide and six feet long, and even as he lay 
quietly awaiting what fate brought to great cat- 
fish, he sang, both theme and accompaniment, 
His whole being throbbed with the continuous 
deep drumming as the thin, silky walls of his 
swim-bladder vibrated in the depths of his body. 
The oxygen in the air was slowly killing him, 
and yet his swan song was possible because of an 
inner atmosphere so rich in this gas that it would 
be unbreathable by a creature of the land. Nerve 
and muscle, special expanse of circling bones, 
swim-bladder and its tenuous gas—all these com- 
bined to produce the aquatic harmony. But as 
if to load this contented being with largesse of 
apparently useless abilities, the two widespread- 
ing fin spines—the fins which correspond to 
our arms—were swiveled in rough-ridged cups 
at what might have been shoulders, and when 
