468 BULLETIN OF THE BUREAU OF FISHERIES. 
(55) THE HILDENBRANDIA ASSOCIATION. 
Hildenbrandia prototypus is common on stones and rocks near low-water mark and 
extending into deep water, where it grows in 114 to 14 fathoms (most plentiful in 4 to 
10 fathoms); it is widely distributed in the Bay and Sound (chart 264). The species is 
found in both the cool- and warm-water sublittoral formations. 
(56) THE LITHOTHAMNION ASSOCIATION. 
Lithothamnion polymorphum grows on stones and shells in fairly deep water and is 
rather widely distributed in the Bay and Sound (chart 265). It was dredged in 2 to 15 
fathoms (most plentiful in 4 to 10 fathoms) over sandy, shelly, and stony bottoms. 
Lithothamnion, although never found in abundance, is present in both the cool- and 
warm-water sublittoral formations. 
(57) THE MELOBESIA ASSOCIATIONS. 
Melobesia farinosa is fairly common on Fucus vesiculosus, Chondrus, Phyllophora, and 
Zostera at low-water mark and below, being dredged in 314 to 11% fathoms, at scattered 
stationsintheSound. The species isa member of the warm-water sublittoral formation. 
Melobesia Lejolisit is very abundant on Zostera throughout the Bay and Sound in 
both shallow and deep water; it was dredged in 2 to 1214 fathoms. The species prefers 
rather sheltered waters, where it may cover the eel grass with a thin incrustation; it is 
characteristic of the Zostera formation. 
Melobesia membranacea is occasionally found on Chondrus and Phyllophora, generally 
in exposed situations as off Gay Head, Cuttyhunk, and Penikese. It was dredged in 
3% to 10 fathoms and clearly belongs to the cool-water sublittoral formation. 
Melobesia pustulata is common on Ascophyllum, Chondrus, and Phyllophora, and is 
present in both shallow and deep water, being dredged in 1% to 14 fathoms off Gay 
Head, Cuttyhunk, and in the easterly portion of the Sound. The species has a scattered 
and probably rather general distribution along the shore and is a member of both the 
cool- and warm-water sublittoral formations. 
THE COOL-WATER SUBLITTORAL FORMATION. 
The cool-water sublittoral formation of the summer contains a number of very 
interesting and characteristic alge, some of which are limited in their distribution to the 
exposed waters off Gay Head and the reefs of Sow and Pigs. Other species have a more 
extended range throughout the lower portion of Buzzards Bay and the westerly portion 
of Vineyard Sound. Finally there is a group of species which, while most abundant in 
the regions described above, are also found in other portions of the Bay and Sound, where 
they form a part of the sublittoral flora characteristic of these more sheltered, and in 
the summer, warmer waters. 
‘The species in these lists preceded by an asterisk (*) are the larger or more abundant 
forms which dominate the formation; species which are rare or occasional are followed 
by an (0). 
The most interesting and noteworthy species in this formation are those which are 
especially characteristic of the cold waters north of Cape Cod and have been recorded only 
