462 BULLETIN OF THE BUREAU OF FISHERIES. 



(29) THE CHANTRANSIA ASSOCIATIONS. 



Chantransia virgatula is abundant, fringing the leaves of Zostera, and is a conspic- 

 uous member of the Zostera formation (c). Chantransia secundata is sometimes com- 

 mon on Zostera, Ceramium rubrum, and Porphyra laciniata. Chantransia Thuretii .is 

 occasionally found in quantity on Ceramium rubrum and on Cystoclonium purpurascens 

 at a depth of 1 to 3 meters (off Juniper Point). 



(30) THE NEMALION ASSOCIATION. 



Nemalion multifidum is a very characteristic summer species, frequently forming a 

 broad zone on rocks a little above low-water mark. This is, perhaps, the best illustration 

 of a red alga with life habits in this region apparently demanding a certain degree of 

 exposure to the air. 



(31) THE ANTITHAMNION ASSOCIATION. 



Antithamnion cruciatum proved to be very widely distributed during the summer in 

 Vineyard Sound and Buzzards Bay, attached to stones and larger algae in 3 to 15 fathoms 

 (chart 239). It frequently forms dense epiphytic growths on Chondrus, Phyllophora, 

 and Polyides. The species is a common member of the warm-water sublittoral formation 

 (b), but it is also found in exposed situations, as off Gay Head and Cuttyhunk. The 

 other species of Antithamnion are not found in sufficient quantity to form conspicuous 

 associations. 



(32) THE CALLITHAMNION ASSOCIATIONS. 



Of the five species of Callithamnion found in this region only three forms develop 

 growths so extensive as to be worthy of consideration in this connection. 



Callithamnion roseum is common during the summer in the more sheltered waters 

 of the Bay and Sound, growing on stones, shells, larger algae, and Zostera in 3 to 13 

 fathoms. It is especially abundant in the easterly portion of Vineyard Sound, where 

 Chondrus, Phyllophora, and Sargassum frequently support heavy epiphytic growths. 

 The species is a characteristic member of the warm-water sublittoral formation (b). 



Callithamnion Baileyi and C. Baileyi var. laxum are also common during the summer, 

 but generally only as scattered plants. Callithamnion Baileyi grows on rocks, and is also 

 frequently epiphytic on larger algae, such as Chordaria and Ceramium rubrum, in the 

 upper level of the sublittoral. It was dredged in 3 to 13 fathoms attached to Des- 

 marestia, Chondrus, Phyllophora, and Cystoclonium. The species seems to prefer the 

 conditions of the warm-water sublittoral formation. 



(33) THE CERAMIUM ASSOCIATIONS. 



Of the six species of Ceramium present in these waters, C. rubrum deserves the 

 most attention, on account of its abundance and very wide range (chart 240). This 

 species is conspicuous in the upper level of the sublittoral, as one of the commonest 

 members of the zone of red algae frequently found on rocks a little below low-water 

 mark in company with such forms as Polysiphonia fibrillosa, P. urceolata, P. violacea, 

 and Chondrus crispus. Ceramium rubrum is also abundant in deeper water, and was 



