Sewellels are medium-sized terrestrial rodents, with no postorbital process to the skull, which is depressed in form, and rootless cheek-teeth, among which the premolars number I, the first in the upper jaw being very small.
The members of this genus were small or medium-sized ungulates with single-rooted incisors.
It was black and white, as hairy as a skye-terrier, and as large as a medium-sized spaniel.
They are all small or medium-sized mountain ruminants, for the most part European and Asiatic, but with one North American representative.
P. Gerardiana, a north-west Himalayan species, is a medium-sized tree with a conical head, growing on the more elevated parts of the mountain range; it furnishes edible seeds.