( xlv ) 



Frinqilla coelehs), for every subspecies {Papilio priamiis poseidon, Pnpilio 

 priamns priamus, Papilio priamus coelestis). If the classifier wishes to represent 

 the probable phylogenetic origin of the nnits which stand co-ordinated in his 

 system and nomenclatnre, he has to take recourse to the figurative tree, or must 

 give a kind of pedigree, as we have done in the present work. Fringilla coelebs 

 does not mean that coelebs is a derivation from Fringilla, but that it forms part 

 of the genus Fringilla : and Papilio priamus poseidon must not be interpreted 

 as signifying that poseidon is derived from priamus, but that it is one of the 

 several components wliich together form the species Papilio priamus. This 

 confusion of ideas has been occasioned by the unfortunate habit, which many 

 classifiers cannot shake off, of regarding the first-described comi)onent as the 

 typical form of a species, as the " Stammart,"' * as the phylogenitically oldest 

 portion of the species, or in the case of a genus as the phylogenetically oldest 

 species of the genus, while it is merely the accidentally first-baptised form. Is 

 the distinction between what is phylogenetically and what is nomenclatorially 

 the oldest really difficult to perceive and to comprehend ? 



The classification of the lower categories from individual variety to species 

 is in a different position to that of the higher categories (from genus upwards). 

 While the species and varieties are realities which can be tested by observa- 

 tion of the live specimens and by experiment, there is no such test possible in 

 the case of genera, tribes, families, etc. These higher categories are definable 

 groups of allied species. The criterion of their being realities, or, as one is 

 used to say, of their being natural, is threefold : — 



(1) The grouj) must be definable — i.e. must not so intergrade with another 

 that there is no line of division, or that the line of division is arbitrary. 



C^) The contents of each group must be homogeneous. Elements of 

 different origin, though perhaps similar in consequence of convergent development, 

 must not be brought together. 



(3) Each higher category must have a separate definition based on other 

 characters than those referred to in the definitions of the respective lower 

 categories. The characters which make an animal specifically distinct do not 

 make it also generically distinct, nor can the same character \\\w\\ which a genus 

 is based be employed to characterise a tribe or a family. 



To define genera and higher units is not always an easy matter. In order 

 to render a definition precise, a close study is necessary of the forms which 

 come under the unit defined, as well as of the forms of the allied units. The 

 difficulties encountered have induced many authors, especially in Ornithology 

 and Entomology, to propose names for genera, subfamilies, and families without 

 attempting a definition. The naked names thus introduced are a fit testi- 

 monium paupertatis for their authors. In our opinion, the thoroughness of the 

 researches in systematic work can best be estimated from the degree of exactness 



* The word '■ Stamm.ait " is much eiiiplo3'ed by Gcrmau writers in this erroneous and misleading 

 sense. .See Reichcnow, in Verh. V. Intfi-n. Zool. Cumjres.i p. yil (I'JO'i). 



