54 
OUE LOCAL MAEINE ALGAE. 
By W. H. young, F.Z.S., F.R.H.S. 
Seaweeds are amongst those kinds of vegetation which are mostly 
looked upon with some contempt as being of little direct use or interest. 
They are, however, of considerable scientific interest in many ways ; 
and as they aftbrd a home and a source of food to a great many 
small marine animals, which in their turn form the principal food 
of the larger Crustacea and fishes, they have an importance of their 
own, differing only in degree from that of the animal life of the ocean. 
It is possible to divide the marine algae of our coast into three 
main divisions according to their colour, and these divisions also 
roughly correspond to their distribution in depth of water. The 
ChlorophycefB, or green weeds, are mainly found near high water 
mark, and being exposed to strong light, their green colouring 
matter serves the same purpose as the chlorophyll of land plants, 
and is identical with it. The Ph£eophycege, or olive brown weeds, 
occur not only between tide marks but beyond, in the form of the 
brown tangles (laminaria), &c., and constitute by far the greatest 
proportion in number of the weeds, though not in species. They 
are easily proved to be really plants possessing chlorophyll by treat- 
ment with fresh water, which dissolves out their brown pigment 
(phycophoeine), leaving the green visible. The Rhodophycete, or red 
weeds, are found generally shaded from the light by the overhanging 
masses of brown weed, in the narrow clefts of the rocks, and 
at the greatest depths. It has been proved that their red colour 
(phycoerythrine) is in most cases only a mask for the essential 
green ; although the precise influence which this red colour exerts 
on the blue and green rays of light — the only ones which filter 
through to such depths — is one of the many interesting scientific 
problems still awaiting complete solution. 
It is probable that on our coast seaweeds rarely occur beyond 
15 to 20 fathoms, since no specimens of living weed from any such 
depths have been brought under my notice during the past year. 
It is many years since Professor G. S. Brady, F.R.S., published 
his detailed list of the Marine Algae of Northumberland and Durham, 
and with the exception of a general catalogue of the algte of Great 
Britain, issued by Messrs. Batters and Holmes in 1892, in which 
the east coast of England is included, no special attention has been 
