612 
surface water in this area. In some specimens («), the frond is not incised in its 
whole length but has broader portions with more or less entire border, and in 
these specimens ramification by proliferations may occur just as in the typical 
species. Other specimens have not such dilatations of the frond and only branch 
by lateral ramification, never by proliferations (8, tenuis Lyngbye). This form has 
certainly arisen by branching of the broader form («). It occurs partly together 
with the latter, partly alone, in the innermost waters (Great Belt and Western 
Baltic). It is interesting to note that in the southernmost part of the area of 8 a new 
form arises as branches from it, branching just like it by lateral ramification only, 
but entirely wanting the lacinulæ characteristic of 8 (fig. 528). — Ph. Bangii is able 
to vegetate and propagate by continued growth and ramification and decay by 
degrees of the lowermost part of the frond; it can therefore be maintained for a 
very long time even if renewal by transformation of the typical form only rarely 
occurs. In this respect it can be compared with the floating forms of Sargassum 
in the Sargasso Sea. The number of specimens of Ph. Bangii in the Danish waters 
is much larger than that of the typical Ph. epiphylla. 
J. SCHILLER has designated the formations of loose Algæ as "Migrationsforma- 
tionen”! or wandering formations; this designation would not, however, be particul- 
arly well-suited to the loose Algze mentioned here, because they live in localities 
where the movements of the water are feeble and where the loose Algæ to a great 
extent are retained and entangled between Zostera-plants or attached Algæ; they 
are, therefore, practically resident on the same spot. 
1 J. SCHILLER, Uber Algentransport und Migrationsformationen im Meere. Revue der ges. Hydro- 
biol. u. Hydrogr. Bd. II, H. 1 u. 2. 
