( 42.) 
these are in nine cases out of ten objectionable), where you 
could state, as fully as your materials permit, all the facts 
about similar varieties pairing—at a guess how many you 
caught, and how many now in your collection? TI look at this 
fact as very important ; if not in your book, put it somewhere 
else, or let me have cases.” * 
Remembering that Mr. Roland Trimen, F.R.S., had expressed 
the same opinion as the result of his wide and long experience 
of South African butterflies, I asked him if he would kindly 
furnish me with a statement. His reply, dated Dec. 28, 1903, 
is as follows :— 
** Dec. 28, 1903. 
“T have noticed the tendency of the sexes of a variety to 
pair together rather than with other varieties in the numerous 
cases of captured pairs sent to me by correspondents in South 
Africa, and sometimes in cases of the same kind which occurred 
to myself when collecting. The species which particularly 
attracted my notice in this way during my visit to Natal was 
Hypanis acheloia (= Gitzius, Herbst, part), which is curiously 
variable on the underside, from pale creamy to deep chocolate. 
I did not know of its seasonal variation at the time, but I was 
in Natal just at the change of season from wet to dry, when 
the intermediate gradations were about, and I was struck with 
the close resemblance of the sexes in pairs that I caught. I 
am sorry to have nothing more definite to give on this head ; 
it is a point much requiring exact and prolonged observation.” 
Mr. Trimen furthermore entertains no doubt that much, if 
not all, of the material upon which he based the conclusion 
that the individuals of the same race tend to interbreed, 
exists, distinctively labelled, in the South African Museum, 
at Cape Town. It is greatly to be hoped that collectors will 
in future carefully label all specimens captured in cottu, and 
that the fact will be recorded on the labels in museums and 
in private collections. It is tantalising to reflect upon the 
number of interesting and important questions which could 
be now decided if this practice had prevailed during the past 
fifty years. The question of the possible origin of species 
* “More Letters,” vol. i, p. 215, Letter 148, 
