Perhaps you are thinking of:
* Red-eared mangabey: This species lives in the rainforest of Central Africa.
* Spot-nosed Guenon: This monkey lives in the forests of West and Central Africa.
* Red-capped mangabey: This species lives in the rainforests of central and western Africa.
Please provide more information about the monkey you're asking about, such as its appearance, location, or any other distinguishing features, and I'll be happy to help!