VII. The development and certain points in the adult structure of the starfish asterias rubens, L

Abstract

The Asteriadse rank among the Cryptozonia of Sladen (87, xxiiiet seq., xxxiv), since they possess reduced marginal plates, while their papulæ or gills are not confined to that part of the abactinal surface which is bounded by the supero-marginal plates. Further, they carry stalked pedicellariæ both of the crossed and the straight varieties; they have never spinelets grouped in a paxilliform manner, and, except in early stages, their tube feet are arranged in quadriserial order. At the present time the development of four starfish has been followed out. These areAsterina gibbosa(Ludwig, 52; MacBride, 55);Asterias vulgaris(Agassiz, 1; Goto, 33);Cribrella oculata(Masterman, 60);Solaster endeca(Gemmill, 29). Much work has also been done on other but often unidentified larval forms. There need only be mentioned at this stage the classical papers of J. Müller (74), the ‘Echinodermenlarven’ of Mortensen (71), and the studies of Metsclinikoff (63), Bury (8, 9) and Field (23).