Zool. Anz. xxvii. 1904, p. 223.
The name seems first to have been used by Klein in 1734, "Naturalis dispositio Echinodermatum" (Danzig). Leuckart about 1850 first established Echinodermata as a primary division of the animal kingdom.
In the Synaptidae the radial canals although present in the young are lost in the adult (Ludwig, 1892, in Bronn's Thier-Reich, Bd. ii. Abt. 3, Buch i. p. 460).
Ludwig, loc. cit. p. 357.
This classification is substantially that suggested by Jeffrey Bell, Catalogue of British Echinoderms in the British Museum, 1892, except that Bell separates Holothuroidea from all others. Reasons will be given later for regarding Holothuroidea as modified Echinoidea.