ANTHBOCERID SPECIES. 545 



for A. trifolii gradually fail for this species, whilst the same ground has 

 become remarkable for the abundance of A. hippocrepidis. It may be, 

 of course, that two distinct species have occupied for a considerable 

 time the same ground, and that what we have observed has been 

 simply a natural fluctuation in relative abundance and scarcity. Still, 

 we cannot forget that we have seen hundreds of A. trifolii in these 

 fields, with here and there a six-spotted hippocrepidis among them, 

 that of late years trifolii has disappeared, and that hippocrepidis has 

 taken its place, whilst the extreme males of hippocrepidis are still almost 

 indistinguishable superficially from A. trifolii. All these difficulties 

 face one in the study of the Anthrocerids, and still one asks, as yet in 

 vain, What is a species ? The specialisation of A. hippocrepidis 

 males is exactly parallel with that of A. ochsenheimeri, a fine race 

 occurring in the southern Alps, richly coloured and thickly scaled, but 

 with the 6th spot reduced in the males often nearly to vanishing 

 point. [This is exactly the opposite result to that occurring in A. 

 viciae where, in the assumed transalpine form, charon, Hb., a 6th 

 spot is developed.] Yet the female ochsenheimeri is indistinguishable 

 from many typical filipendulae, and the same is true of female hippo- 

 crepidis, Stephs. The life-history of the latter is still unpublished (and 

 practically unknown) ; it may be identical Avith A. filipendulae, it may 

 be very different therefrom. Our ignorance makes us form opinions, 

 and opinions based on ignorance are always bad. One feels, however, 

 that it is better to keep all these forms distinct rather than lose them 

 by a lumping process that is bad in itself and unscientific in principle. 

 One other point is worthy of mention. We forwarded to Fletcher, in 

 1894, $ oclisenheimeri and eggs, from Courmayeur. Some of those 

 bred in 1895 were characteristically marked with a small 6th spot. 

 The most extreme forms in this direction were crossed, and in 1896 

 others with spot 6 almost absent were obtained. In 1897, and 1898, 

 careful selection and inbreeding had got rid of spot 6 altogether, and 

 an artificial 5-spotted form had been obtained. These, although very 

 similar in appearance to the 5-spotted A. lonicerae, refused to pair 

 therewith, but paired freely with A. filipendulae, of which A. ochsen- 

 heimeri appears to be only an alpine variety. That is, Fletcher's examples 

 appear to have maintained the separate genitalia of A. filipendulae, 

 whilst spot 6 has been suppressed, and a race produced superficially 

 resembling the 5-spotted species. We should like to have compared 

 actual specimens of yurda and mersina with Harwood's Essex aberra- 

 tions, but the continental material was not forthcoming, and this 

 remains among the problems for future investigation. 



The old notion that species should breed true fails utterly when 

 applied to the Anthrocerids. Some hybridise freely, and cross-pairing 

 occasionally takes place in the most erratic manner (ante, pp. 418-419). 

 It is clear that some well-defined Anthrocerid species that inhabit the 

 same ground are able to pair, if so disposed, and produce fertile 

 progeny, yet the species are maintained pure in their breeding-grounds, 

 often five or six species occurring in a very restricted habitat. Inability 

 to cross can, therefore, hardly be considered a test of species among 

 the Burnets, and if this were taken as a test, we should perhaps have 

 to reduce our European species to something less than a dozen, and 

 yet, while quite able to cross, they rarely do so in nature, so far as our 

 observations go. The species are generally well-defined in colour and 

 markings, and the variation of each takes its own lines, so that diffi- 



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