Volume S of this series comprises an introduction to echinoderms and systematic descriptions of fossil Homalozoa and Crinozoa. Following the standard editorial preface, the introductory section contains two papers of importance to all students of the Echinodermata, whether dealing with fossil or recent material. The first article, by Ubaghs, is an essay on the general characters of the phyllum, and although it is only just over 50 pages in length it is quite remarkable in scope and detail. Several planes of bilateral symmetry are recognised—to the dismay of those only. conversant with the Lovenian echinoid orientation—and those of Loven and Carpenter are correlated differently to the interpretation previously given in this series by Fell and Moore (1966). Ubaghs regards all homologies based on the various planes of reference as not proven and also regards Fell's analogy betwen somasteroid virgulia and crinoid pinnulate arms as rather superficial. He notes that associated Lower Ordovician crinoids and somasteroids appear more distinct than their extant relatives. The Echinodermata are divided into the four subphyla Homalozoa, Crinozoa, Asterozoa, and Echinozoa, and the included classes are discussed. All classes are assumed to have become differentiated by the early Paleozoic or earlier. If a bilaterally symmetrical pre-echinoderm form existed a pre-Cambrian time is assumed for it. The affinities of the phylum are discussed and all known echinoderms are regarded as too specialised to have given rise to another phylum. Alleged affinities between “carpoids” and larval Amphioxus and stylophorans (or cystoids) and ostracoderms are“ . . .based on superficial analogies or erroneous interpretations. . .” The fundamental distinctions between echinoderm stereom and vertebrate bone are emphasised. (In Millott 1967, stylophorans are regarded as chordates, and a sipunculoid ancestor for the echinoderms is discussed).