NOTES—ORIGINAL AND SELECTED. 207
Canton Zurich, was invaded by an immense swarm of butterflies, principally C.
cardui, over half a mile wide, and the procession was so long that it took two
hours to pass ; they flew from 3ft. to 12ft. above the ground, and went in a north-
westerly direction.''
* * * * *
" Previous to the great "Cardui year" of 1879 an extraordinary flight of
these butterflies passed over the island of Vido, of the Ionian group, in 1872;
the swarm reached the island about 9 a.m., and continued passing for over three
hours. Traces of the flight were evident in the channel of Corfu, as large
numbers of butterflies were seen floating on the surface of the water, and for some
days after they were seen drifting into the bays of the island of Corfu. As long
ago as 1828 the migratory habits of this butterfly were recorded, as in that year
an account is given in the Annales des Sciences Naturelles of an extraordinary
swarm which was seen in the month of May in one of the cantons of Switzerland,
their numbers were so enormous that they occupied several hours in passing over
the district where they were observed."
" I have just received a letter from my friend Mr. Alpheraky, the experienced
Russian zoologist, containing such interesting remarks concerning the occurrence
of C. cardui in Russia that I take the opportunity of quoting his observations.
He says: 'I have inhabited a country (Taganrog on the Azoff) where it is by far
the commonest butterfly I know of. Every year I have seen it in great quantities,
but in exceptional years I have seen such extraordinary swarms of this butterfly
that, except perhaps in some valleys of the Tian-chain mountains, I have never
seen anything comparable to the millions of millions of C. cardui near Taganrog.
The Taganrog type is of a brilliant pinkish colour, such as I have not seen in any
other locality, and I remember that my friend Staudinger, the greatest
lepidopterists of all times, was quite astonished when I sent him some of the
specimens. I have gathered the pupae whenever I wanted them by hundreds in
the space of an hour or so, in any place where Carduus or Cnicus grew. This
butterfly has a very curious habit of following any vehicle that travels fast, for
miles, exactly in the manner that porpoises follow a ship, remaining for some
minutes behind, then overtaking the horses, and so on. In autumn I have seen
them in such numbers on different flowers that I have taken nets full at a time
just to see how many I could catch at a stroke, and strange to say all my
endeavours to obtain varieties failed all the specimens have always proved to be
typical ones. The type I found in Turkistan is much paler than our Russian
one.'"
Mr. Frohawk's article is illustrated by a drawing showing
the transformations of the butterfly, done in his inimitable
manner, and it is one of the most interesting accounts that has
appeared of this visitation.
BOTANY.
Asplenium Ruta-Muraria (the Wall-Rue Fern) in
Essex.—This plant, though widely distributed over Essex
is decidedly rare—at all events as compared with some other
counties. In many parts of Sussex, for instance, I have seen it
flowering in profusion on almost every old wall.