BIOLOGICAL SURVEY OF WOODS HOLE AND VICINITY. 467 
shelly, and stony bottoms, and it is also abundant in shallow water along shore. In 
sharp contrast to L. rosea, this species is characteristic of the warm-water sublittoral 
formation (B) and prefers sheltered situations where it frequently accompanies Champia 
parvula. 
(50) THE RHODYMENIA ASSOCIATION. 
Rhodymema palmata, the dulse, is found chiefly in the lower portion of Buzzards 
Bay and westerly portion of Vineyard Sound (chart 259). It was dredged in 1 to 19 
fathoms (most plentiful in 4 to 12 fathoms) growing on stones and larger alge, over 
sandy, shelly, and stony bottoms. A prominent member of the cool-water sublittoral 
formation (A), this large species is conspicuous for its size, although the growths in this 
region are never extensive. 
(51) THE DELESSERIA ASSOCIATION. 
Delesseria sinuosa is practically restricted to the lower portion of the Bay and 
westerly portion of the Sound (chart 260). It grows on larger alge, such as Chondrus 
and Phyllophora, occasionally on stones, and was dredged in 14 to 17 fathoms (most 
plentiful in 4 to 12 fathoms). The species is a member of the small group of alge 
peculiar to the exposed conditions off Gay Head and Cuttyhunk, and is one of the 
noteworthy forms in the cool-water sublittoral formation (A). 
(52) THE GRINNELLIA ASSOCIATION. 
Grinnellia americana is almost universally distributed throughout the Bay and Sound 
(chart 261). It was dredged in 2 to 19 fathoms (most plentiful in 4 to 12 fathoms) on 
stones and shells, over sandy, shelly, stony, and muddy bottoms, but it likewise comes 
close to the surface, as on piles of wharves (Little Harbor, Woods Hole). Although 
apparently in all regions of the sublittoral, this species is partial to the more sheltered 
situations, and consequently warmer waters, where it is one of the most characteristic 
and abundant forms together with A gardhiella tenera and Champia parvula. 
(53) THE POLYIDES ASSOCIATION. 
Polyides rotundus, although never abundant, has a rather wide distribution in both 
the Bay and Sound (chart 262). It is found only in fairly deep water, 114 to 15 fathoms 
(most plentiful in 4 to 10 fathoms), over sandy, shelly, and stony bottoms, occasionally 
over mud. ‘The species is a member of both the cool- and warm-water sublittoral forma- 
tions, and is conspicuous for its size, although the plants grow in scattered groups. 
(54) THE CORALLINA ASSOCIATION. 
Corallina officinalis grows in dense patches over rocks in exposed situations below 
low-water mark and to a considerable depth; the species is widely distributed in the more 
open portions of the Bay and Sound (chart 263). It was dredged in 4 to 1ofathoms, over 
sandy, shelly, and stony bottoms. ‘The associations of Corallina are generally so dense 
that they occupy the surface of their attachment to the almost complete exclusion of 
other alga; the species is present in both the cool- and warm-water sublittoral formations. 
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