PHYSETER, in zoology, a genus belonging to the order of Cete. It has teeth in the under jaw, and a filula in the head or snout. There are four species, viz. 1. The catodon, with a filula in the snout, and having no back-fin. 2. The macrocephalus has a filula in the neck, and no back-fin. The spermaceti is extracted from the ventricles of its brain. 3. The microps, with a long fin on the back, and the upper jaw much longer than the under one. 4. The turlio, with a very high fin on the back, and the points of the teeth blunt. All the four species are inhabitants of the northern Ocean.