Monkeys are probably among of the most popular and interesting animals in the world. There are a number of monkey varieties. New world monkeys are distinguished from the old world monkeys of Africa and Asia by certain features of appearance and size. The new world monkeys (platyrrhines) are small to medium-sized. They have wide circular nostrils and long tails, which are prehensile or semi-prehensile. They do not have cheek pouches and buttock pads. Prehensile tails can be called an extra hand that helps a monkey swing, touch and grasp things