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
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 anyone 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.
First: According to magnitude I divide the whales into three primary books (subdivisible into chapters ), and these shall comprehend them all,