Traditionally, species have been treated as classes or kinds in philosophical discussions of systematics and evolutionary biology. Recently a number of biologists and philosophers have proposed a drastic revision of this traditional ontological categorization. They have argued that species ought be viewed as individuals rather than as classes or natural kinds. In this paper an attempt is made to show that (a) the reasons advanced in support of this new view of species are not persuasive, (b) a reasonable explication can (...) be given of the treatment of species as classes that is consistent with current theory and practice in evolutionary biology and systematics, and (c) that once certain confusions concerning the species concept have been clarified, there are good theoretical grounds for maintaining that species are best viewed as classes or kinds. (shrink)