( 458 ) 



ouc ill a nomenclatorial sense. Mor])hology and nomenclature come into contest if 

 we employ tbe old style of naming the forms, while the contest is entirely avoided 

 by accepting our method, according to which the species Ilepialua humuli comprises 

 two forms, Hepiulus humuli humuli and Hepialus humuli hethlandicus. 



A sjiecies of Pieiis was described by Linnd in 175S as Pierii »api, while 

 the Alpine and boreal variety of it, which has a different appearance, received 

 in 1808 the name of Pieris bryoniae. From the experiments with this insect 

 carried out by Weismann and others, the inference has been drawn * that bryoniae is 

 phylogenetically the older one of the two forms, and that, therefore, the species ought 

 to bear the younger name of bryoniae instead of the older name of napi. As the 

 meaning of Pieris napi var. bryoniae, which is the name of the Alpine and boreal 

 butterfly according to the old style of nomenclature, is that bryoniae is a variety 

 originated in consequence of the variation oi napi, an alteration is indeed necessary 

 if the above iuterj)retation of the experiments is correct, and thus evolutionists would 

 have to phi}' havoc with the names of all those numerous species of which a younger 

 form happens to be described first. We have, however, endeavoured to showf that the 

 species is represented neither by the white form napi, nor by the darker form bryoniae, 

 but is composed of napi and bryoniae ; the species is not congruent with the 

 ancestral form of the recent forms, but is congruent with the sum of the recent 

 forms, and its name is, therefore, independent of the name of that form whicli 

 is supposed to be phylogenetically the oldest of the component forms. According 

 to our method of nomenclature the name of the species in question would be 

 Pieris napi, the name of the Aljnne and boreal form P. napi bryoniae, and that 

 of the form inhabiting the rest of Central and Northern Europe P. napi napi. 

 If in theoretical treatises it is necessary to distinguish nomenclatorially the oldest 

 from the younger forms of a species, it conld be done by adding (f. prim.) = forma 

 primiyenia, or some such sign, to the name — P. napi bryoniae (f. ])rim.). 



The various jioints in these introductory notes have been very cnrsoril}- dealt 

 with: but we are in hopes that the remarks, in spite of their shortness, will serve to 

 explain our interpretation of the facts of variation we are now going to bring before 

 the reader. 



II.— THE VARIATION OF THE GENITAL AUMATUltE OF 

 CERTAIN PAPILIOS. 



The prehensile organs situated round the orifice of the sexual system of insects 

 liave for about fifty years been made use of for diagnostic purposes, and it was, and 

 is, a general belief tliat the genital armature is of such gre.it constancy in every 

 species that peculiarities exiiibited by certain individuals in these internal 

 ectodermal organs, and not found in other individuals which otherwise are very 

 sliglitly different from those, are of specific value. As we have shown in the 

 introduction that every individii.il lias its individual ])ecnliarities, a slight dis- 

 tinguishing character of an individual, besides the sexual armature, can alwjiys be 

 found, and therefore the above opinion leads practically to the assertion that 

 a specimen with some kind of peculiarity in the sexual armature is specifically 

 distinct from the specimens which do not have that peculiarity. On the other hand, 



• Weismann, Stiidiet in the Theory of Dctcent I. London, 1882. pp. 61 ff. 



t Compare also Lorenz, Sitz.-Ber. zool. int. On. Wien 1892. p. 17 ; .Jordan, Nov. ZoOI.. ISK. p. 1S2 ; 

 Hartert, Jbit 1896. p. 363. 



