Menopome (Protonopsis horrida), a large North American amphibian in the Salamander order. It is widely distributed in the rivers of the Mississippi basin, and is well known as the 'hell-bender,' 'alligator,' 'water-dog,' &c., names which suggest its fierce characteristics. It resembles the salamander in form, has four well-developed limbs, and a persistent gill-aperture. It attains a length of 18 inches to 2 feet, and has extraordinary powers of voracity and vitality.