AUTHORITIES.--In addition to the works referred to at the beginning of the article, the following deal with the general subject: Bather, Gregory and Goodrich, "Echinoderma," in Lankester's _Treatise on Zoology_ (London, 1900); F.J. Bell, _Catalogue of the British Echinoderms in the British Museum_ (London, 1892); P.H. Carpenter, "Notes on Echinoderm Morphology," _Quart. Journ. Micr. Sci._, 1878-1887; Y. Delage and E. Hérouard, _Traité de zoologie concrète, iii., Échinodermes_ (Paris, 1904); A. Lang, _Text-Book of Comparative Anatomy_, transl., part ii. (London, 1896); Ludwig and Hamann, "Echinodermen," in Bronn's _Klassen und Ordnungen des Tierreichs_ (Leipzig, 1889), in progress; M. Neumayr, _Die Stämme des Tierreiches_ (Wien, 1889); P.B. and C.F. Sarasin, "Über die Anatomie der Echinothuriden und die Phylogenie der Echinodermen," _Ergebnisse naturw. Forsch. auf Ceylon_, Bd. i Heft 3 (Wiesbaden, 1888); R. Semon, "Die Homologien innerhalb des Echinodermenstammes," _Morph. Jahrb._ (1889); W.P. Sladen, "Homologies of the Primary Larval Plates in the Test of Brachiate Echinoderms," _Quart. Journ. Micr. Sci._, 1884; K.A. v. Zittel, _Handbuch der ... Paläozoologie_, i. pp. 308-560 (München, 1879); also Grundzüge, translated and revised by C.R. Eastman as _Text-Book of Palaeontology_ (New York and London, 1899). The larger treatises here mentioned contain very full bibliographies, and a complete analytical index to the annual literature of the Echinoderma has for many years been published in the _Zoological Record_ (London). (F. A. B.) FOOTNOTE: [1] Sometimes called "Echinodermata," a Greek name meaning "sea-urchin-skins," which was invented by J.T. Klein (1734) to denote the tests of the Echini or sea-urchins; its later use for the animals themselves, or for the whole phylum, was an error in both history and etymology. ECHINUS (Gr. for "hedge-hog" or "sea-urchin"), in architecture, the convex moulding which supports the abacus of the Doric column. The term is sometimes given to the _ovolo_ of the Ionic capital, especially when curved with the egg-and-tongue enrichment. The origin of this use of the word in architecture, which comes down from ancient times, is uncertain.