At dinner Colin turned the conversation to swordfish and their ways.
"There's one thing I don't quite understand, Dr. Jimson," he asked, "is a spear-fish the same as a swordfish, only that the weapon is shorter?"
"Not at all," was the reply, "the spear-fish is a variety of the great sailfish, which you see in West Indian waters six or seven feet long,
with a huge dorsal fin, blue with black spots, looming above the water like the sail of a strange craft. But the real difference is in the spear or sword. In the case of the spear-fish it is bony, being a prolongation of the skull; in the case of the swordfish it is horny, and horns, as you probably know, are formations of skin rather than bone. Now the narwhal's tusk," he continued, "is again an entirely different thing."
"That's a tooth, isn't it?"
"Yes," was the reply, "it seems to be the mark of the male narwhal. Sometimes a narwhal has two tusks, but generally only one—on the left side. The females have none at all. You know the unicorn is always represented with a narwhal's tusk? One of the early travelers, Sir John de Mandeville or Marco Polo, I forget which, brought back a narwhal's tusk which, he had been told, had been taken from a kind of horse. I really suppose that the native who sold it believed it was from some species of antelope. But to this day the arms of Great Britain show a horse having a fish's tooth sticking out from his forehead like an impossible horn."
"Way-o!" suddenly came the cry from the masthead.
"Where away?" called the captain, jumping up and looking around.
"Three points on the starboard bow, sir," answered the sailor, pointing his finger.