VII. LIST OF THALLOPHYTES OCCURRING BELOW THE 
10-FOOT LEVEL. 
EXPLANATION OF TABLE G. 
In addition to the algx, 2 bacteria, 2 lichens, and 2 bryophytes have been 
recorded. All of these are given at the end of this list of alge. The names 
used for green alge are those of F. S. Collins (Chlorophycee of North America). 
pa used for the Pheophycee and Rhodophycee are chiefly from Farlow’s 
“ Marine Alge of New England.” 
While the number of lower plants growing on the east and et shores, 
between the 9-foot and 12-foot levels, may be considerable, they are, as far as 
noted, such as occur far above sea-level. Therefore, aside from the alge of the 
fresh-water rivulets, they are not here listed. The lichens and mosses of the 
Spit, even from the top, are included, because this is such an essentially littoral 
habitat. 
Symbols are given for part of the forms only in this table, these being the ones 
whose distribution is indicated by means of these symbols on plates rx and x. 
In cases where the distribution was not determined separately for each of the 
several species of a genus, the same symbol has been used on the maps to indicate 
any species of the genus found in a given locality. This collective use of a 
symbol is indicated in Table G by a bracket embracing the various species 
included under it. 
The characters of the plants and their environments which are noted in 
Table G are those given for the vascular plants, with the exception of “ light 
demands.” ‘These are omitted because few definite and significant data are 
available. Of course, many of the alge of the bottom and wharves, growing 
between tide-marks, are in a sense shade plants, protected by submergence, as 
was suggested in regard to Zostera and Ruppia in Section V. Other alge 
growing between the 4-foot and %-foot levels among the stalks of Spartina 
glabra, S. patens, and the Salicornias are also shaded by these larger plants. 
Other species still, like those of Calothrix and Lyngbya, grow in full sunlight 
on the open beach, or on the wharves even near the 8-foot level. These are 
subjected to rather intense light and desiccation, and during neap tides may 
not be touched by the water for several days together. Finally, the alge of the 
Inlet below —1.5 feet and those of fresh-water streams are never exposed to 
full sunlight. 
Certain alge, e. g., Ulva, Agardhiella, Fucus vesiculosus spiralis, etc., may 
persist for weeks or months unattached to the substratum. Where a species may 
occur free in this manner this fact is indicated in the column for substratum by 
the symbol “ fr.” 
Since none of the alge penetrate far into the substratum, the salinity of the 
soil-water is of little consequence to them. The salinity of water surrounding 
the shoot is the thing of importance, and it is this, therefore, that is given in 
the list. This salinity may, as is indicated, differ greatly at different stages of 
the tide. This is especially true for plants living near fresh-water streams. But 
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