Note: Information is dated. Do not rely on it.Porcupine. A name of certain rodent quadrupeds, the best-known European species of which belong to the genus Hystrix. The body is covered, especially on the back, with the so-called quills, or dense solid spine-like structures, intermixed with bristles and stiff hairs. The muzzle is generally short and pointed, the ears short and rounded. The anterior feet possess four and the hinder feet five toes, all provided with strong thick nails. The common or crested porcupine, Hystrix cristata, found in southern Europe and in northern Africa, is the best-known species. When fully grown it measures nearly two feet in length, and some of its spines exceed one foot. Its general color is a grizzled dusky black. The spines in their usual position lie nearly flat, with their points directed backward; but when the animal is excited they are capable of being raised. The quills are loosely inserted in the skin, and may, on being violently shaken, become detached. In America two species of arboreal porcupines are found, both belonging to the genus Erethizon. They inhabit the northeastern states and Canada.