[24] E.g. Bouvier, Le Natural, 1889, p. 242.
[25] Köhler, Zool. Jahrb. vii. 1893, p. 1 f; Haller, Arb. Zool. Inst. Wien, x. p. 71.
[26] Plate, SB. kön. Preuss. Ak. Wiss. Berl. 1893. p. 959.
[27] E.g. Pelseneer, Bull. Sc. France Belg. xxiv. p. 347 f.
[28] E.g. Bergh, Zool. Jahrb. v. p. 1 f.
[29] Calkins, Amer. Nat. xi. p. 687.
[30] One step even further (or perhaps it should be termed a branch derivative) is seen in the genus Smaragdia, which is probably a Neritina which has resumed a purely marine habit of life.
[31] SB. Naturf. Gesell. Leipz. 1886–87, pp. 40–48.
[32] L. and F. W. Moll. of India, iv. p. 167.
[33] T. Scott, Journ. of Conch. v. p. 230.