Zoological Researches and Illustrations, v. "On Polyzoa." Cork, 1830.
"Symbolae Physicae," 1831, and Abh. Ak. Berlin, 1832, i. p. 377, etc.
T. cit. p. 92.
Vol. i. 1880, Introduction, p. cxxxi.
Élémens de Zoologie, 2nd ed. Animaux sans Vertèbres, 1843, pp. 238, 312. Prof. A. Milne-Edwards has kindly written to me, informing me that he believes this to have been the first occasion on which the term was thus used.