How far this form of respiratory mechanism is distributed amongst Ophiurids it is impossible to say. It was first observed by me in the case of Ophiothrix fragilis at Plymouth in 1905, but since then I have found it in Ophiura ciliaris and in Amphiura squamata.
"Neue Beitr. zur Anat. d. Ophiuriden," Zeitschr. wiss. Zool. xxxiv. 1880, p. 340.
"Bewegungen d. Seesternen," Mitth. Zool. Stat. Neapel, vii. 1886-87, p. 123.
Bell, "Contribution to the Classification of Ophiuroids," Proc. Zool. Soc. 1892, p. 175.
Hamann, Bronn's Thier-Reich, Bd. ii. Abt. 3, Ophiuroidea, 1900, p. 910 f., discriminates a family Ophiodermatidae, but gives no character by which it can be distinguished from Ophiolepididae.