1945] Notes on Neotropical Plebejince 5 
basis of genitalia reflects natural relationships better than do 
other principles. I think the answer is “yes.” 
A “polytypic genus” is determined by structural characters 
which are common to all the species it includes and the par- 
ticular combination of which, more than the presence of some 
particular detail, no matter how striking, distinguishes the group 
from any other. A “monotypic genus” ( i.e ., a structurally iso- 
lated species which does not fit into any known generic group) 
obviously lacks the first feature while the number of characters 
entering the distinctive combination is vastly increased by prac- 
tically coinciding with the whole array of specific characters, so 
that the only “reality” a monotypic genus has, lies in the im- 
plication that the only species it contains is the only one 
“known” and that if others were “known,” a common denomi- 
nator now “hidden” in the monotypic genus would be revealed. 
Among polytypic genera, a “natural genus” is one which reflects 
the flickering, as it were, of a strongly differentiated type of 
combinational structure within limits as narrow per se as, say, 
the range of continuous variation within a structurally highly 
polytypic species, and thus consists of specific structures re- 
sembling each other more than they do any other species. If 
h 1? h 2 , h 3 , h 4 denote the interspecific hiatuses, and H 4 , H 2 , etc. 
the intergeneric ones, then the lesser the h’s and the larger the 
H’s, the more “natural” the genus is — and the more liable it is 
to be transformed into a polytypic species by the next reviser 
with more material at his disposal. 
A certain harmony, as yet rather obscure, seems to exist be- 
tween a particular type of male armature and a particular fe- 
male one; this has been taken into account in founding the 
genera discussed below. The impression I have formed so far 
that with “natural genera” specific differentiation in these or- 
gans is more marked (or at least easier to observe) in the male 
may be due to insufficient investigation, but anyway I cannot 
find any exact correlation between female lock and male key. 
In what manner and to what extent the sclerotized parts of the 
sexes in Plebejince fit each other during copulation is not clear, 
but I doubt whether the valves, the termination of which is 
evolutionally the most vulnerable part, come into any direct 
contact with such structures in the female organ that might lead 
to some intersexual adaptation. 1 
1 Lorkoviz states (1938, Mitt. Munchner Ent. Ges. 28:231) in an admirable 
paper on the European representatives of Everes ( Everince ) that in that genus 
