Hag (Myxine glutinosa), the popular name for an aquatic chordate animal, the type of a family (Myxinidae), to which the name is often extended, and which, with the Lampreys, makes up the order Cyclostomata or Round-mouths, The eel-shaped body is scaleless, the single nasal aperture is immediately above the mouth, which is furnished with four pairs of barbules; there is one tooth in the middle of the palate, and two rows of comb-like teeth on the tongue. Along each side of the body forming a bead-like chain are glands which pour forth the mucus from which these creatures derive their generic and specific names. In the genus Myxine, with three species, there is one external branchial aperture on each side of the abdomen, leading by six canals to as many gill sacs. In the only other genus (Bdellostoma) with two species there are at least six such apertures on each side, each communicating directly with a separate gill sac. The distribution of the family corresponds with that of the cod family, upon which the hags prey, penetrating into their bodies and feeding on their flesh, whence the common species is also called the Borer.