Journ. Mar. Biol. Ass. vol. iii. 1893-1895, p. 22.
Quart. J. Micr. Sci. vol. xxiii. 1883, p. 349; Ibid. vol. xxvii. 1887, p. 605.
Cf. Willey, Amphioxus and the Ancestry of the Vertebrates, Macmillan, 1894.
Ann. Sci. nat. 7, sér. vol. xiii. 1892, p. 321.
E. Rohde, SB. Ak. Berlin, 1892, p. 515.