The term 'Monkey with a Long Tail' is referring to the Titi monkey, which is a species of New World monkey found in South America. It is known for its long tail, which can be up to twice as long as its body. The Titi monkey is an arboreal species, meaning it spends most of its time in trees, and is found in tropical and subtropical forests. It is a social species, living in groups of up to 10 individuals.