See Poulton, Tr. ent. Soc. London, 1884, p. 51; op. cit. 1892, p. 293; and Bateson, p. 213; Gould, p. 215.
Giraud, Ann. Soc. ent. France (4), v. 1865, p. 105; Fauvel, l.c. Bull. p. liii.
For a table, see Meyrick, l.c.
Barrett, "Increasing Melanism in British Geometridae," Ent. Monthly Mag. 1895, p. 198.
P. Zool. Soc. London, 1892, p. 192.