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 Thureti 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 alge 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 alge, 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. Cadllithamnion Bazleyi grows on rocks, and is also 
frequently epiphytic on larger alge, 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 alge frequently found on rocks a little below low-water 
mark in company with such forms as Polystphonia jibrillosa, P. urceolata, P. violacea, 
and Chondrus crispus. Ceramium rubrum is also abundant in deeper water, and was 
