4 Psyche [March-June 
exclude each other and so it may happen that two structurally 
distinguishable local forms belong to one species allopatrically 
because they racially intergrade, but at the same time belong to 
different species sympatrically because in some other region 
their structural counterparts occur side by side without inter- 
breeding (this incidentally is the position in Lycceides) . In such 
cases one should give precedence to the all important sympatric 
moment and find somewhere in the spirals of racial intergrada- 
tion a point at which the whole system can be elegantly, in 
the mathematical sense (for we are dealing with measurable 
structures), divided into two parts, i.e., two species, using some 
combination of trinomials to designate this or that interspecific 
form (e.g., Lycceides scudderi doei Roe trans ad melissa roei 
Doe). This state of affairs is not a flaw in the concept of “spe- 
cies” but an indirect result of its dual nature (“structure” plus 
“reproduction,” “male” plus “female” etc.) and should be ac- 
cepted by the taxonomist with perfect equanimity. 1 
The impact on the eye of a combination of characters in the 
whole structure or in an element of it, results in the perception 
of certain structural types. Structures of the same type imply 
phylogenetic affinities unless it can be proved, as in some cases 
it is easy to do, that the resemblance is “false” i.e., attained by 
essentially different means. Such false resemblances are ex- 
tremely rare and the number of characters involved is small, 
and this is as it should be, since such “convergence” depends 
upon the mathematics of chance. False dissimilarities also occur 
(and are also rare), i.e., the striking difference between one type 
and another is seen, when analysed, to be due to a simple and 
brief process of evolution in an unusual direction. 
Unless we believe that certain structural resemblances and 
dissimilarities are not due to chance or to gross adaptional 
modifications, but can be classified according to their phylo- 
genetic sense, all horizontal genera are artificial groupings — of 
some practical use to collectors (e.g., the convenient lumping of 
all small blue butterflies with rounded hindwings and dotted 
undersides in one “genus”) but of no scientific value. This 
brings us to the question as to whether a classification on the 
1 “Subspecies” (on which I hold rather special views which I shall discuss else- 
where) may be briefly defined as a locally constant phase of specific alar char- 
acters with or without a local fixation of some stage within the graded variational 
range of the specific genitalic structure. The days are quite gone when easy-going 
describers could give names to these things without a detailed study of genitalic 
and pattern characters throughout the polytypic species or genus involved. 
