Moseley, Challenger Reports, Zool. xxii. 1887, p. 267.
C. W. Wilson, Journ. Morph. xv. 1899, p. 667.
Burckhardt, Ann. Mag. Nat. Hist. (7), vi. 1900, p. 568.
Ibid. op. cit. p. 558.
Wiliamson, Phil. Trans. cxxxix. 1849, p. 435; Hertwig, Morph. Jahrb. ii. 1876, p. 328; v. 1879, p. 1; vii. 1882, p. 1; Klaatsch, ib. xvi. 1890, p. 97 et seq., p. 209 et seq.