THE BROWN SEAWEEDS OF THE SALT MARSH. 345 
Other Records of this Marsh Form. 
Although the marsh form of Fucus ceranoides has not been recognised 
hitherto, there is a small specimen in the British Museum Herbarium which 
probably belongs to this dwarf form. It is labelled “J. Cocks, Algarum 
Fasciculi, 1855-60," and was originally named F. ceranoides ; but below is 
written F. vesiculosus ? It is 6 cms. high by 10 ems. across, and has neither 
attachment dise nor fruiting branches nor adventitious shoots. The descrip- 
tion runs :—“ A plant that grows in ditches, or places where freshwater 
streams are occasionally overflowed by the sea. Not very common.” 
Near Laira Lake, Plymouth, Torbay, and coast of Cornwall. 
Although there is no evidence as to whether this plant was attached to 
stones or embedded in the mud of these ditches and streams, and it is 
difficult from a dried specimen of this antiquity to recognise the charac- 
teristic delicacy of the thallus, it seems very probable that this is a specimen 
of the dwarf embedded variety of К. ceranoides, similar to that found at 
Keyhaven. We have not had the opportunity of visiting the localities given 
to investigate the matter. 
THE ORIGIN AND STATUS OF THE MARSH Fucorps. 
On British salt marshes, five out of the seven upper littoral rock species 
of the Fucoideæ are represented, and very probably the only reason for 
the absence of Fucus serratus, Halidrys, and Cystoseira is their extreme 
intolerance of desiccation. It is noteworthy that three species of Cystoseira 
occur in the loose-lying formations of the Adriatic Sea (Schiller, 1909, p.72). 
It is quite possible that Aimanthalia will be found on the salt marsh. 
In their new habitat striking morphological peculiarities arise, which, in 
some cases, are so great that the marsh forms have been designated as distinet 
species. Where direct evidence is available, as in the case of Ascophyllum 
nodosum v. scorpioides (Reinke, 1892, p. 11, and Oltmanns, 1905, ii. p. 233), 
it points to the production of these curious forms by direct vegetative 
budding from detached portions of the thallus of normal plants. But this 
evidence is difficult to obtain upon salt marshes, because, once the ground 
has been infected, vegetative reproduction continues on a large scale from the 
marsh form itself, so that the extensive areas may be covered by the products 
of one individual. In certain cases, even the access of normal plants to the 
marsh may be only occasional. For example, the nearest station to the Black- 
water marshes for Ascophyllum nodosum, the parent of the var. scorpioides, 
which is quite abundant there, is Burnham-on-Crouch—eight or ten miles 
and the presence of Ascophyllum in the drift along 
south of the Blackwater 
the Blackwater is sporadic. 
