Monkeys have altogether too many common names. This one, Colobus guereza, can be called the Mantled Guereza, the Eastern Black and White Colobus Monkey, or the Abyssinian Black and White Colobus Monkey, etc. Makes me wish for the American Ornithological Union, that assigns to birds official English common names as well as Latin scientific names.
Colobus Monkeys and the closely-related Asian Langurs eat mostly leaves and have complex, multi-chambered stomachs to help digest them. Consequently, they sit around for much of the day, digesting massive leafy pulp.
There’s a vivid diorama of the Colobus Monkeys’ treetop habitat in the Museum of Natural History’s Hall of African Mammals.