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148 NOTES ON KANGE IN DEPTH OF MARINE ALG.E.
Mentha hirsuta, b. subglabra, -BaA;er. Leouurus Cardiaca, Linn.
M. sativa, b. paludosa, Sol. • Carduus Forsteri, Linn.
Ballota ruderalis, Fi-ies (the true Ruppia i-ostellata, Linn.
plant). Clienopodium urbicum, Linn.
Excluded Species.
Erysimum orientale, Br. Waste Eosa pomifera, Hern. Coppice
ground, near the docks, Q-lou- wood, near Painswick.
cester. Achillea nobilis, Linn. Waste
Melilotus parvillora, Lam. Banks ground, near the docks.
of the Severn, opposite the docks, Centaurea centaurioides, Linn.
Gloucester. Banks of the Severn, near the
docks.
NOTES ON RANGE IN DEPTH OF MAEINE KhGM.
By Professor Dickie.
{^Eead to the Botanical Society of Edinburgh ; Revised by the Author.)
The bathymetrical range of animal life has been of late attracting a
due share of attention, and facts of great interest have been ascertained.
Very little has been done regarding the range in depth of marine plants ;
few instances have been recorded, and even some of these are not quite
trustworthy.
When the dredge ceases to scrape tlie bottom, it becomes in its pro-
gress to the surface much the same as a tovving-net, capturing bodies
which are being carried along by currents, and therefore great caution
is necessary in reference to any marine plants found in it. Seaweeds
are among the most common of all bodies carried by currents near
the surface or at various depths below, and from their nature are very
likely to be entangled and brought uj).
The present communication is offered chiefly with tlie view of di-
recting attention to the ^ubject, and of recording a few facts, which
may, perhaps, stimulate algologists to add to the number of such.
There are two effects which diminished supply of light at great
depths may be expected to produce u[)on Alga;,—decrease of size and
modiiication of colour. The proportion of light necessary for the ger-
mination of the spores, and subsequent development, surely deserves
the attention of physiologists.*
* In ' Annals of Natural Ilistory,' De(\ 1868, there are some remarks by
Mr. Jeffreys regarding various Mollusca, with bright-coloured shells and welldoveloped
eyes, at depths from 200 to mure than 1500 fathoms.