THE TRUE FISHES. 161 
are found on both sides of the Atlantic, and from Brazil 
to Cape Cod. They are very ferocious. Allied is the 
thresher shark 
(Fig. 198). The 
tail is fully a 
third of the en- 
tire length, and 
forms a terrible 
weapon when 
swung about by FIG. 198.—Thresher shark. 
the powerful 
fish. They attain a length of twenty feet. 
Man-Eater Shark (Zamnide).—The great Carcha- 
rodon has been known to attack boats. Their enormous 
mouths contain six or eight rows of serrated teeth. They 
have a wide geographical range, are mainly pelagic, living 
in the open sea. One species (C. gangeticus) lives in an in- 
closed lake in the Feejee Islands, breeding above the falls. 
It has also been found at Bagdad, three hundred and fifty 
miles from salt water. A shark is also found in Lake 
Nicaragua. The largest shark of this family ever caught 
was thirty-six and a half feet long, from Australian waters. 
NotTr.—In repeated observations of these and allied sharks attack- 
ing objects on the surface and on the bottom, on the outer Florida reef, 
in no case did they turn on their backs. In attacking a cow they ran 
their snouts out of the water, and bit as do ordinary fishes, tearing and 
shaking the body like a dog. One, caught after a struggle of two hours, 
during which it towed the boat a long distance, contained among other 
curiosities the hoofs of an ox, a mass of old rope, a tin can, and other 
material obtained near a slaughter-house. They never attacked human 
beings in this locality, though bathing and swimming from key to key 
was often indulged in, where twelve and fourteen foot sharks were 
observed only a few moments before. 
Basking Shark (Cetorhinide).—Bone-shark, sail-fish, 
and many other titles are applied to these sharks, that are 
the largest of all fishes. One, captured by the schooner 
