Biol. Centralbl. xiv. 1894, p. 53.
Forel's latest views on this subject will be found in the Ann. Soc. ent. Belgique xxxvii. 1893, p. 161; the very valuable paper by Emery, in Zool. Jahrb. Syst. viii. 1896, p. 760.
Ann. Soct. ent. France, 1893, p. 467.
Ann. Soc. ent. France, 1893, Bull. p. cclxiv.
Forel, J. Bombay Soc. viii. 1893, p. 36.