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. 



Rhodymenia palmaia, the dulse, is found chiefly in the lower portion of Buzzards 

 Bay and westerly portion of Vineyard Sound (chart 259). It was dredged in i to 19 

 fathoms (most plentiful in 4 to 12 fathoms) growing on stones and larger algae, 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 algae, such as Chondrus 

 and Phyllophora, occasionally on stones, and was dredged in lyi to 17 fathoms (most 

 plentiful in 4 to 12 fathoms). The species is a member of the small group of algae 

 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 americatia 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 Agardhiella tenera and Champia parvvla. 



(53) THE POLYIDES ASSOCIATION. 



Polyides roiundus, although never abundant, has a rather wide distribution in both 

 the Bay and Sound (chart 262). It is found only in fairly deep water, iX 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 10 fathoms, 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 algae ; the species is present in both the cool- and warm-water sublittoral formations. 



