ared on the chalk facing of the embankment by
Ditton Station. It has remained there several years and grown into a
vigorous specimen. Two or three smaller examples are now seen by it,
doubtless sprung from some of the hundreds or thousands of seeds shed by
the original one plant. The species is not included in Salmon and Brewer's
_Flora of Surrey_.

"The main line of the railway has introduced into Ditton parish the
perennial _Arabis hirsuta_, likely to become a permanent inhabitant. The
species is found on the chalk and greensand miles away from Thames Ditton;
but neither in this parish nor in any adjacent parish, so far as known to
myself or to the authors of the flora of the county, does it occur. Some
years after the railway was made a single root of this _Arabis_ was
observed in the brickwork of an arch by which the railway is carried over a
public road. A year or two afterwards there were three or four plants. In
some later year I laid some of the ripened seed-pods between the bricks in
places where the mortar had partly crumbled out. Now there are several
scores of specimens in the brickwork of the arch. It is presumable that the
first seed may have been brought from Guildford. But how could it get on to
the perpendicular face of the brickwork?

"The Bee Orchis (_Ophrys apifera_), plentiful on some of the chalk lands in
Surrey, is not a species of Thames Ditton, or (as I presume) of any
adjacent parish. Thus, I was greatly surprised some years back to see about
a hundred examples of it in flower in one clayey field either on the
outskirts of Thames Ditton or just within the limits of the adjoining
parish of Cobham. I had crossed this same field in a former year without
observing the Ophrys there. And on finding it in the one field I closely
searched the surrounding fields and copses, without finding it anywhere
else. Gradually the plants became fewer and fewer in that one field, and
some six or eight years after its first discovery there the species had
quite disappeared again. I guessed it had been introduced with chalk, but
could obtain no evidence to show this."

4. Mr. A. Bennett, of Croydon, has kindly furnished me with some
information on the temporary vegetation of the banks and cuttings on the
railway from Yarmouth to Caistor in Norfolk, where it passes over extensive
sandy Denes with a sparse vegetation. The first year after the railway was
made the banks produced abundance of _Oenothera odorata_ and _D