First:  The uncertain, unsettled condition of this science of Cetology is in the very vestibule attested by the fact, that in some quarters it still remains a moot point whether a whale be a fish.  In his System of Nature, A.D. 1776, Linnaeus declares, “I hereby separate the whales from the fish.”  But of my own knowledge, I know that down to the year 1850, sharks and shad, alewives and herring, against Linnaeus’s express edict, were still found dividing the possession of the same seas with the Leviathan.

The grounds upon which Linnaeus would fain have banished the whales from the waters, he states as follows:  “On account of their warm bilocular heart, their lungs, their movable eyelids, their hollow ears, penem intrantem feminam mammis lactantem,” and finally, “ex lege naturae jure meritoque.”  I submitted all this to my friends Simeon Macey and Charley Coffin, of Nantucket, both messmates of mine in a certain voyage, and they united in the opinion that the reasons set forth were altogether insufficient.  Charley profanely hinted they were humbug.

Be it known that, waiving all argument, I take the good old fashioned ground that the whale is a fish, and call upon holy Jonah to back me.  This fundamental thing settled, the next point is, in what internal respect does the whale differ from other fish.  Above, Linnaeus has given you those items.  But in brief they are these:  lungs and warm blood; whereas, all other fish are lungless and cold blooded.

Next:  how shall we define the whale, by his obvious externals, so as conspicuously to label him for all time to come.  To be short, then, a whale is a spouting fish with a horizontal tail.  There you have him.  However contracted, that definition is the result of expanded meditation.  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.  But as these pig-fish are a noisy, contemptible set, mostly lurking in the mouths of rivers, and feeding on wet hay, and especially as they do not spout, I deny their credentials as whales; and have presented them with their passports to quit the Kingdom of Cetology.