For recent accounts of the anatomy, embryology, and ethology, cf. C. H. Eigenmann, Bull. U.S. Fish Comm. for 1892, p. 381, and Arch. Entwickelungsmech. iv. 1896, p. 125.
It has recently been ascertained, on a large number of specimens, that in the African species the female alone performs the buccal nursing duties.
Cf. Monograph by J. Pellegrin (Paris, 1904).
Gerbe, Rev. et Mag. de Zool. xvi. 1864, p. 255.
Zool. Garten, 1867, p. 148. See also Verrill, Amer. Journ. Sci. (4) iii. 1897, p. 136.