Tail rather short, clothed with short depressed hairs.
The spines are mixed with long soft hairs.
The gall is cup-shaped, and its outer surface is crumpled and covered with small warts and hairs.
They include three genera, of which the first is represented by the Canadian porcupine (Erethizon dorsatus), a stout, heavily-built animal, with long hairs almost or quite hiding its spines, four frontand five hind-toes, and a short, stumpy tail.
They are of a lighter build than the ground-porcupines, with short, close, many-coloured spines, often mixed with hairs, and prehensile tails.