( Lexx ) 
paper describing mimicry in 8. America, pays particular 
attention to the question of the perfect matching of two 
insects of a pair. Thus he says (Trans. Linn. Soc., vol. xxiii, 
p. 501) : “* The process of the creation of a new species I believe 
to be accelerated in the I[thomiae and allied genera by the 
strong tendency of insects, when pairing, to select none but 
their exact counterparts,’ and again, on p. 513 he says: 
“. . the one exact counterfeit, whose exactness, it must be 
added, is henceforward kept up to the mark by the insect 
pairing necessarily with its exact counterpart.” 
Charles Darwin (as Prof. Poulton pointed out in his Presi- 
dential address to the Ent. Soc., 1904) at once saw the impor- 
tance of this, and wrote to Bates in 1862 (‘ Life and Letters,” 
vol. u, p. 392): “ I wish, however, you had enlarged a little 
more onthe pairing of similar varieties ; a rather more numerous 
body of facts seems here wanted.” Again on November 25 
(1862?) he wrote: ‘Could you find me some place, .. . 
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 ? 
I look at this fact as very important.” Subsequently, Charles 
Darwin rather severely criticised the statements of Bates 
above alluded to. At the close of his review of Bates’ paper 
in the Natural History Review for April 1863, article 17, 
pp. 223, 224, he says : ““ We will only notice briefly one other 
point which has an important bearing on the production of 
new species and races; namely the statement repeatedly made 
that in certain cases the individuals of the same variety 
evince a strong predilection to pair together. We do not 
wish to dispute this statement; ... But we are by our 
profession as critics bound to be sceptical, and we think 
that Mr. Bates ought to have given far more copious evidence.” 
I am much obliged to Prof. Poulton for telling me of this 
interesting passage. 
Prof. Poulton, in his address mentioned above, quotes a 
letter from Trimen on this subject, who says : “ I have noticed 
the tendency of 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 
