In 1843, Hermann Burmeister published his view on trilobite taxonomy and how the group related to other organisms, living and extinct, in the work "Die Organisation der Trilobiten aus ihren lebenden Verwandten entwickelt". He considered the trilobites to be crustaceans, as previous authors had, and classified them together with what he assumed to be their closest relatives, "Eurypterus" and the genus "Cytherina", within a clade he named "Palaeadae". Within Palaeadae, Burmeister erected three families; the "Trilobitae" (composed of all trilobites), the "Cytherinidae" (composed only of "Cytherina", an animal today seen as an ostracod) and the Eurypteridae (composed of "Eurypterus", then including three species).