Lemurs have their roots in ancient Roman times. These ghosts were so important to the Romans that a whole mythos was built around them. The lemur was known as a malignant entity. A wandering type of ghost, it is said to carry anger and hostility over having its earthly life cut short and not having the proper funeral rites given.
Also a lemur can be the ghost of a person who had died without the benefit of a family. Basically, the lemur is a very angry wandering ghost. As in the example of the doppelgängers, the lemur is often associated with darkness, doom and misfortune. The fear was so great in encountering a lemur that the ancient Romans set aside certain days in the month of May to appease these ghosts. This was known as Lemuralia. But when we strip away the allure of ancient Roman mythology, the lemur just seems to be a combination of an apparition and a phantom.