160 BRITISH MARINE ALGA. 
pore through which the spores are finally liberated.’’ Fig. 148 represents 
a frond of the beautiful and very rare species, Stenogramma wterrupta. 
The fronds of this plant arise from a small discoid root. The stem, which 
is very short, soon expands into a broad, fan-shaped branching membrane ; 
the segments are flat and cleft, somewhat in the manner of those of 
Rhodymenia palmetta (Fig. 143), but the colour is much brighter and 
richer, being a deep rose-red, especially so when the plant is in fruit, and 
then it is impossible to mistake this brilliant species for anything else.’ 
The narrow line or nerve which traverses the segments of the frond, but 
broken or interrupted here and there by a short space, is thickened about 
the centre, and is of a brilliant crimson. These swollen portions of the 
nerve contain the conceptacles, which at maturity are filled with a vast 
number of very minute spores. Fig. 148 (b) represents a vertical cutting 
of a conceptacle, the spore mass within raising the upper and depressing 
the under surface of the central portion of the segment, the inner stratum 
being composed of large colourless cells, the rich red endochrome being 
confined to the external layers of small cells on each surface of the 
frond. This rare plant is annual; it is taken in Cork Harbour; at 
Minehead, in Somerset; and washed ashore in several situations near 
Plymouth. Usually, British specimens are from 2in. to 5in. long, but I 
have dredged some in Plymouth Sound, which were over 8in. long, and 
several of the divisions which had been injured at the tips had thrown out 
Fie. 148. (a) Stenogramma interrupta; (b) Vertical cutting of conceptacle 
magnified. 
a new series of segments from the broken parts, all of which were branched 
in the same manner as the primary frond. This curious plant is found on 
the Californian and Spanish coasts, and at New Zealand. It was formerly 
called Delesseria interrupta by the elder Agardh ; butits more recent name 
