NOTES ON THE ZTG^NIDF.S. 167 



encore capture qu'un seal specimen de cette vari^t6 ; tandis que dans 

 la tfifolii des plaines du centre de la France (laquelle trifnlii de nos 

 pays differo un peu de celle du Midi) la continence est tres commune " 

 { Etudes (VKntomohviii', " Lep. des Pyrenees," p. 31), I have a note 

 to the effect that this form = Hiibner's aclullcac, Eur. SvhwHt., fig. 

 165. As for the type form, it can usually be recognised without 

 difficulty. I have taken typical specimens of this species quite in- 

 distinguishable from those obtained at Strood, York, Mansfield and 

 other British localities, at Courmayeur (Piedmont, 3,500 ft.) August, 

 1894, on the summit of the Mendel Pass (Tyrol, 4,000 ft.), where 

 it was just emerging, from July 28th to August 3rd, 1895, on the 

 zigzags between St. Michel de Maurienne and Valloire (Dauphine, 

 4,000 ft.), just emerging on July 27th, 189G, on the hills of Gresy- 

 sur-Aix, on July 25th and 26th, 1896, and other localities. The 

 capture of the typical form of this species in abundance at Mendel 

 from July 30th-August 3rd was interesting, as Dr. Chapman and 

 Mr. Lemann had previously taken worn Z. vicdtcai/inis on the same 

 ground, the species being quite over before X. louiceiac appeared. 



In a letter written to me in May, 1893, referring to the fertility of 

 the hybrids of Z. hmicerae and Z. trifolii, which he had just proved 

 so conclusively, W. H. B. Fletcher writes : — " I am not at all prepared 

 to admit that the fertility of hmiccrae-trifolii hybrids proves that these 

 species are but one. Many hybrid plants are fertile, as are also some 



hybrid water-fowl I am inclined to think that Z. hniircrae and 



trifolii are good species." This opinion, from fZ/c entomologist who has 

 had so much experience in breeding hybrid species, and from whose 

 experiments all our data with regard to hybrid Zygiienids have been 

 obtained, is exceedingly valuable. 



Barrett [lirit. Lep., ii., p. 158) says that he has " described Z. 

 hmicerae and Z. trifolii as distinct in deference to the universal admis- 

 sion of them as separate species .... but they are exceedingly difficult 

 to separate in the perfect state .... But the difficulty has been very 

 seriously enhanced by the discovery that they not only pair together 

 with perfect freedom, but produce fertile eggs, which produce, in due 

 course, moths having intermediate characters, or the characters in 



part of both parent races These experiments render it difficult 



to believe that what we call by the two names (trifolii and lonicerae) 

 are more than local races of the same species very rarely found inter- 

 mingled." We criticise this statement with some diffidence, knowing 

 that Mr. Barrett is a firm believer in the original creation of species, 

 a determined opponent of the principles of evolution in every shape 

 and form, and a disbeliever in the efficacy of natural selection ; still 

 we are constrained to ask what explanations he would offer as to the 

 following queries based on facts, so far as our own experience goes : 

 (1) Why may one breed hundreds of either Z. trifolii and Z. lonicerae 

 without getting any doubtful forms ? (2) Why, if they are forms 

 of one species, do they separate into one invariable ionn = lonicerae, and 

 two variable forms = trifolii and trifdii-major f (3) Why these forms, 

 being widely distributed over the British Isles and the Continent, 

 maintain their absolute distmctness, with neither of them anywhere 

 having a claim to be considered a local form which has diverged from 

 the type? (4) Whether the mere fertility of the lonicerae-trifnlii 

 hybrids is sufficient to prove that they are but one, considering that 



