This list of mythical creatures that begin with this letter and I am constantly gathering information from each continent, and is continually being updated.
Cericopithicus (Medieval Bestiary)
Cericopithicus is a species of ape described in some medieval bestiaries. It is said to always give birth to twins, of which it will always hate one and love the other. The callitrix, cynocephalus and satyrus apes of medieval bestiaries are described as doing this. The cericopithicus apes are said to have long beards and wide tails.
All that is provided about this ape is that it has a tail. Carl Linnaeus is quoted as saying that the satyrus is "hairy, bearded, with a manlike body, gesticulating much, very fallacious, is a species of monkey, if ever one has been seen."