452 MR. E. A. L. BATTERS ON 
they turn yellowish, and then the plant looks more like an 
Ectocarpus than a Phyllitis. The fructification is produced on 
fronds scarcely thicker than a hog’s bristle. In structure and 
fructification this plant agrees with Phyllitis Fascia, from which 
it can at all times be distinguished by its small size and fibrous 
root. It seems to be a winter annual, making its appearance 
about the middle of December, and having quite disappeared 
by the end of February. 
RALFSIA sPONGIOCARPA. (Plate XVIII. figs. 17-21.) 
R. nigrescenti-olivacea, tenuis, levis, tota pagina inferiore 
lapidibus adnata, filis erectis simplicibus (vel parce dichotomis) 
articulatis, articulis 1-14 diametro brevioribus, paranematibus 
subcylindraceis, vel superiore parte paulatim attenuatis, sporangiis 
unilocularibus, ovatis, sessilibus vel plus minusve pedicellatis, 
48-52 u longis, 28 u crassis. 
Hab. Berwick-on-T weed. 
An interesting plant growingon the flat slaty bottoms of tide- 
pools half filled with sand at Berwick. To the naked eye it 
closely resembles Ralfsia clavata, Crouan, but the frond is thinner, 
and the fructification much more conspicuous, the difference in 
colour between the fruited and unfruited portions of the frond 
being very apparent. The fronds are from a quarter of an inch 
to an inch in diameter, very thin, and when barren perfectly 
smooth and glossy, circular at first, then, from several becomirg 
confluent, more or less lobed or irregular. The sori, at first 
confined to a narrow ring near the margin of the frond, gradually 
spread inwards until they cover the entire central portion of the 
frond, giving to it a peculiarly spongy or velvety appearance 
under a lens, a characteristic which suggested the specific name. 
The fruited portion of the frond soon becomes detached from the 
stone, and is washed away, leaving only the marginal portion of 
the plant. As this alga fruits in winter, only the very small 
unfruited portions of the plant are to be found in summer ; this, 
coupled with the fact that the pools in which it grows are often 
quite filled with sand, may account for the plant having been 80 
long overlooked. 
From Ralfsia clavata it differs in the shape of the paraphyses, 
which are always cylindrical or slightly tapering to the apex, 
never clavate as in that species. The vertical filaments, which 
sometimes appear to be slightly branched, gradually pass into 
