A walrus spouts much like a whale, but the walrus is not a fish, because he is amphibious.

But the last term of the definition is still more cogent, as coupled with the first.

Almost any one must have noticed that all the fish familiar to landsmen have not a flat, but a vertical, or up-and-down tail.

Whereas, among spouting fish the tail, though it may be similarly shaped, invariably assumes a horizontal position.
By the above definition of what a whale is, I do by no means exclude from the leviathanic brotherhood any sea creature hitherto identified with the whale by the best informed Nantucketers; nor, on the other hand, link with it any fish hitherto authoritatively regarded as alien.* Hence, all the smaller, spouting, and horizontal tailed fish must be included in this ground-plan of Cetology.

Now, then, come the grand divisions of the entire whale host.
*I am aware that down to the present time, the fish styled Lamatins and Dugongs (Pig-fish and Sow-fish of the Coffins of Nantucket) are included by many naturalists among the whales.