The knowledge of the fauna of Suriname is of essential importance in the study of the neotropical Mammalia. The first publications containing information on mammals of Suriname appeared very early in the history of European exploration of South America. Such publications were relatively numerous in the 17th and 18th centuries, when the Republic of the Seven United Netherlands was at the peak of its power, and Suriname was one of its richest colonies. At that time many animals, alive or preserved, were sent from Suriname to the Netherlands. The living specimens were kept in Dutch menageries, while skins and alcohol specimens found their way to private natural history collections (“cabinets of rarities”) of which at that time there was an impressively great number in Holland (see Engel, 1947); several foreign collections received material via the Netherlands. In many instances the Dutch collections formed the basis for, or contributed considerably to, important zoological publications, like those by Albertus Seba (1665-1736), Petrus Artedi (1705-1735), Carolus Linnaeus (1707-1778) and Peter Simon Pallas (1741-1811). Linnaeus (1758), in his fundamental 10th edition of Systema Naturae, based many of his descriptions on Suriname material, either by directly studying this (when in Holland, 1735-1738, Linnaeus must have seen much Suriname material in Dutch collections, while Swedish naturalists like C. G. Dahlberg (1721-1781) and D. Rolander (1725-1793) sent Suriname specimens to Swedish collections), or by referring to previous publications like that by A. Seba. Thomas (1911: 124), when dealing with the type localities of the mammals described by Linnaeus in the 10th edition of his Systema Naturae, stated: “with regard to species named from the figures in Seba’s ‘Thesaurus’, it would not be unjustifiable to suggest that in the case of all tropical South American animals, Surinam — the great source of all Dutch collections — should be accepted as the type locality ....”. No less than 24% of all species of mammals known from Suriname have Suriname as the type locality. It goes without saying that for a better understanding of the relation between the various species, and that between the various subspecies of a single species, it is essential to know the characters of the population of the type locality and of its variability. Therefore, in the present work I have tried to give of every species a description based exclusively on the Suriname material examined by myself (of course with the exception of discoloured, mutilated or abnormal specimens) and also to provide as many illustrations as feasible of such material. I hope, by giving this information, to enable students of the faunae of other parts of South America to obtain a better idea of the status of the Suriname populations. The second object of the present book is to provide a reliable guide for the identification of the species of Suriname mammals, not only to professional zoologists, but also to agriculturists, ecologists and others who in their work in Suriname have to deal with mammals, be it for their control or their protection; furthermore it is intended for anyone (e.g., hunters and naturalists) who just wants to know more about the fascinating creatures that inhabit this beautiful and interesting country. Therefore keys are provided to all the species. In most cases there are two sets of keys, one based exclusively on external characters, the other only on characters provided by the skull. The keys to the skulls are added because skulls and skull fragments of animals hunted or used as food are often found as offal in or near settlements in the interior or as signs of good luck fastened to the roofs of Amerindian and Bushnegro dwellings. In the keys I have tried to employ such characters as are normally still noticeable in the fragments that one usually finds. Another use for the keys to the skulls is to identify skull fragments of small mammals (especially Marsupialia and Rodentia) found in owl pellets or in stomach contents. In some groups the species are very difficult to distinguish on external characters alone, and then the skull characters may be decisive for a certain identification, this being especially true for some groups of Marsupialia, Chiroptera, Cricetidae and Muridae. Illustrations are added as a help with the keys. In using the keys one has to keep in mind (1) that they are based on characters of adult animals in which all molars are functional, and therefore not necessarily will give good results for juveniles, (2) that notwithstanding the long period in which the Suriname mammals have received the attention of zoologists, the Suriname mammal fauna still is far from well known (especially from the interior), and that there undoubtedly are several species which so far have not yet been reported from the country. Therefore a careful comparison with the description and illustrations is most advisable.