572 Professor E. B. Poulton on Mr. Thayer's 
improbable, in the case of the groups hitherto explained 
by the Miillerian or Batesian theories. Of course close 
syncryptic resemblances between bark-like moths, lichen- 
like moths, grass-like and pine-needle-like larvex, etc., 
have been known and admitted for many years. 
Leaving the tropics we find a beautiful example of 
mimicry, Batesian, or more probably Miillerian, which has 
arisen in Mr. Thayer’s own region, and has never wandered 
much beyond it, an example moreover very well known to 
the American artist-naturalist, viz. the resemblance of the 
northern Limenitis (Basilarchia) archippus (misippus) to 
the Danaine intruder from the tropical south, Anosia 
plexippus. 
In this case there is little doubt that the Nymphaline 
has been actually drawn away from an ancestral appear- 
ance, much like that now borne by Z. arthenvis, explained 
by Mr. Thayer as promoting concealment by likeness to 
flower-masses and their background. If therefore Mr. 
Thayer is compelled to admit all this effect produced by 
the Danaine intruder in his own northern region, why 
should he not be ready to accept far more extended effects 
of the same kind in the crowded luxuriant life of the 
tropics ? 
I donot think that naturalists have so entirely misunder- 
stood the principle of a cryptic pattern resembling some 
object in the environment combined with the effacive 
gradation so admirably explained by Mr. Thayer. His 
illustrations of tiger, lion, brilliantly-coloured fish, appear- 
ance of forest and shore birds, etc., all these are accepted 
at once and have been accepted for a long time. But 
naturalists have regarded the skunk as conspicuous, and I 
feel sure that Mr. Thayer will admit that it falls into 
another category from that which includes the forms just 
named. If concealment is brought about by the beautiful 
and delicately adjusted effacive gradation from upper dark 
to under white, as is now generally admitted, surely the 
“slight amount of effacive gradation” of the black 
skunk cannot be the same thing, or belong to the same 
class. 
We must admit Mr. Thayer’s main conclusion, that the 
forms we call conspicuous might be more conspicuous, and 
also accept the statement that a pattern is less conspicuous 
than the monochrome. 
Admitting all Mr. Thayer says, at least of the butterflies 
