What is "physeter macrocephalus"

Sperm whale \Sperm" whale`\ (Zo["o]l.) A very large toothed whale ( Physeter macrocephalus), having a head of enormous size. The upper jaw is destitute of teeth. In the upper part of the head, above the skull, there is a large cavity, or case, filled with oil and spermaceti. This whale sometimes grows to the length of more than eighty feet. It is found in the warmer parts of all the oceans. Called also cachalot, and spermaceti whale.

Pygmy sperm whale (Zo["o]l.), a small whale ( Kogia breviceps), seldom twenty feet long, native of tropical seas, but occasionally found on the American coast. Called also snub-nosed cachalot.

Sperm-whale porpoise (Zo["o]l.), a toothed cetacean ( Hypero["o]don bidens), found on both sides of the Atlantic and valued for its oil. The adult becomes about twenty-five feet long, and its head is very large and thick. Called also bottle-nosed whale.

Ambergris \Am"ber*gris\ ([a^]m"b[~e]r*gr[=e]s), n. [F. ambre gris, i. e., gray amber; F. gris gray, which is of German origin: cf. OS. gr[^i]s, G. greis, gray-haired. See Amber.] A substance of the consistence of wax, found floating in the Indian Ocean and other parts of the tropics, and also as a morbid secretion in the intestines of the sperm whale ( Physeter macrocephalus), which is believed to be in all cases its true origin. In color it is white, ash-gray, yellow, or black, and often variegated like marble. The floating masses are sometimes from sixty to two hundred and twenty-five pounds in weight. It is wholly volatilized as a white vapor at 212[deg] Fahrenheit, and is highly valued in perfumery.
--Dana.

cachalot \cach"a*lot\, n. [F. cachalot.] (Zo["o]l.) The sperm whale ( Physeter macrocephalus). It has in the top of its head a large cavity, containing an oily fluid, which, after death, concretes into a whitish crystalline substance called spermaceti. See Sperm whale.