78 BRITISH MARINE ALG. 
abundantly at Largs, on the Clyde, parasitic on the stems of Desmarestia 
aculeata (Fig. 53). 8. radicans grows on sand-covered rocks, in small 
tufts rarely exceeding an inch in height. S. fusca is a rarity, though 
it was discovered as long ago as the year 1827. It may be known by a 
very peculiar form of ramuli which are borne on some of the filaments near 
the tips. Dr. Harvey describes them as being “attenuated at the base and 
trifid at the apex, the joints of the plant being marked with a pale brown 
band.” The specific name is from the reddish-brown colour of the plant. 
S. racemosa, so named from the clusters of grape-like spores produced on 
each side of the filaments, was discovered by Sir John Richardson in 1821, . 
on the shores of the Frith of Forth. For very many years this curious 
plant eluded the search of algologists in all parts of this kingdom, and 
indeed was generally regarded as a lost species, when all at once, a few 
years since, it was discovered in tolerable plenty, in the river Clyde, by 
Mr. Roger Hennedy. This rare plant I have never met with, and know it 
only by Dr. Harvey’s beautiful figures in his ‘‘ Phycologia.”’ S. plumosa 
(Fig. 79) is, so far as my experience goes, peculiarly an inhabitant of 
northern waters, and even there it is regarded as a rarity. It is said to be 
found at Greenland and in the Arctic regions, while the coast of Corn- 
wall is given as its southern limit. About twelve years ago I took a beautiful 
specimen of this plant in the bay of Lamlash. It was attached to a large 
stone that came up in the dredge from a depth of five-and-twenty fathoms. 
The branches of this species very closely resemble feathers, being regularly 
pinnated with opposite, spreading, generally unbranched pinnz or wing- 
lets, the tips of which are frequently sphacelate or withered. I have 
described this rare and peculiar plant as among the Sphacelariew, but I 
must inform my readers that Professor Agardh, the celebrated Swedish 
) algologist, has removed it from this order, and erected it into the type 
of a new one under the name of Chetopteris, which signifies ‘‘ bristle wing,”’ 
in reference to the erect bristle-like pinnz or ramuli of its branches, the 
original specific and very characteristic name of plumosa being retained. 
Advancing onwards with my description of the Ectocarpacew, I now 
arrive at the genus Ectocarpus, the simplest in point of structure and fructi- 
fication of any of the plants of this order. In tkese the frond is composed 
of a single simple or highly-branched filament, and producing spores and 
active granules or zoospores in pod-like bodies, which are seated on the 
branches of some, or produced conspicuously in the stem or branches 
of other individuals. Many of these fruit-bearing organs afford most 
’ beautiful microscopic objects, as may be seen in the group of: magnified 
portions at Fig. 80. The extreme difficulty of giving anything like a 
satisfactory representation of any living species of Hctocarpus obliges me 
to be content with a slightly magnified portion of one of the shore species, 
and to represent fertile branches of a few others much more highly magnified. 
Fig. 81 represents a lateral branch from a fine specimen of FE. littoralis, 
a common species which is found abundantly on the shore /'uci at all sea- 
sons. The tufts are from 6in. to more than 12in. long, of a brownish- 
