( viii ) 
considerable overlapping of the later A. coridon, and the earlier 
second brood examples of A. thetis in late August and 
September. 
This overlapping has led to a remarkable result, for there 
can be little doubt that occasional cross-pairings take place 
{teste Sabine). Many are recorded in other butterfly species 
(see A Nat. Hist. Brit. Lep., vol. v, chap, i, “ Mongrelisation 
and Hybridisation in Lepidoptera”), but these are from one 
case or other inoperative or ineffective in nature. In these 
two species, however, there can be no doubt that natural 
hybrids occasionally result, to which the identity of habitat, 
overlapping in time of appearance, similarity in habitat, 
almost structural identity of genitalia, actual identity of food- 
plant, all contribute. 
The first of these hybrids was described by Zeller {Stett. 
Ent. Ztg., 1845), from Posen, as poloniis, and is now in the 
Brit. Mus. coll. Two others were known to Zeller. The other 
known examples ai-e:— 
(1) Kerasdere, June 23rd, 1875, Staudinger (Hor. Soc. Ent. Ross., xiv, 
p. 244). 
(2) Pomeranian border of Silesia, Staudinger (7/or. Soc. Ent. Ross.). 
(3) Cuxton, Kent, May 20th, 1893, Tutt (Proc. Ent. Soc. Loud., 
1894). 
(4) Airolo, Ticino, June 1907, Dadd [Proc. Ent. Soc. Land., 1908). 
(5-6) Pyrenees, June 25th, 1907, Keynes [Ent. Rcc., xx., p. 178). 
(7) Plain of Mugnone, end July, Stefanelli (Bull. Soc. Ent. Hal., xxxii, 
p. 339). 
(8) Fiesole, early August, Stefanelli [Bull. Soc. Ent. Bah, xxxii, p. 
339). 
(9) Chateau de la Batiaz, Favre {Mitt. Schw. Ent. GeselL, xi, supp. 
p. 4). 
(10) Vernet les Rains, Oberthiir {Etudes, xx, p. 21). 
(11) Cauterets, Oberthtir {Etudes, xx, p. 21). 
(12) ? Bella Tola, 1878, Forbes {Ent. Mo. Mag., xv, p. 277). 
(13) Digne, Muschamp {Ent. Rec., xxii, p. 30). 
(14) Pfyn, July 1900, Rosa {Ent., xxxv, p. 96). 
(15) Brides-les-Bains, July 19th, 1904, Reverdin {Ent. Rec., xxii, p. 
30). 
(16) Brides-les-Bains, July 1st, 1891, Blachier {Eat. Bee., xxii, p. 30). 
(17) Bois-des-Freres, Geneva, Blachier {Ent. Rec., xxii, p. 30). 
(18) Foot of the Saleve, Blachier {Eat. Rec., xxii, p. 30). 
(19) Fei.stenberg, June 19th, 1900, Presseicker (as hafneri, Veidi. z.-h. 
Ges. Wien, 1908, p. 68). 
(20) Oberfeld, near Wippach, June 28th, 1907, Presseicker (as hafneri, 
Verh. z.-b. Ges. JViea, 1908, p. 68). 
(21) Shar Deresy, North Syria {see Tutt, Eat. Rcc., xxii, p. 30). 
(22-26) Assisi, June and July 1909, Wheeler {Eat. Rec., xxi, p. 
250). 
