Section 1 reviews the concept of idionomy, the lawful condition for the existence of individual things or events and for their aggregates. Contrary to autonomy, idionomy is a relational concept. It refers to a specific cluster of laws, determining a subjective class of individuals besides an objective ensemble of possible variations. Section 2 summarizes various types of these idionomic clusters, to be distinguished by their primary qualification, their secondary foundation, and their tertiary disposition to be interlaced with other clusters. Section 3 investigates whether a biotic species corresponds to an idionomic cluster as described in Sections 1 and 2. I shall argue that the view of biotic species being natural kinds is not at variance with the standard theory of evolution.