GUEREZA, a long-tailed black and white Abyssinian mon key, Colobus guereza, characterized by a long pendent mantle of white hair; the name is sometimes extended to embrace all the African thumbless monkeys of the genus Colobus. These are the African representatives of the Indo-Malay langurs (Semnopithe cus), with which they agree in their slender build, long limbs and tail, although differing by the rudimentary thumb.