UPPER LITTORAL BELT ws 
It is probably limited in distribution upward by its inability to withstand 
desiccation or constant submergence in fresh water. Its lower limit is perhaps 
conditioned by the inadequacy of light and the certainty of being silted over at 
lower levels. 
Porphyra: This alga is represented in summer by a few dozen small plants 
only. ‘They are attached to stakes or to stones or piles of the wharves at, or just 
below, the 4-foot level. It was most frequently found on the wharf of the 
Research Laboratory, though it has also been seen on the east side at 950 south 
and between 1,700 and 2,500 north. An occasional plant may be seen on a stake 
or buoy in the middle of the harbor. In April 1911 we were surprised to find 
thousands of plants of Porphyra from 1 to 2 dm. broad on the pebbles of the 
bottom of the Inlet. Examination of the wharves at this time showed that 
Porphyra was little if any more abundant there than in mid-summer. We have 
already (p. 31) suggested the possible factors limiting the distribution of this 
alga. | 
4. THE UPPER LITTORAL BELT (FROM 6.5 TO 8 FEET). 
The character of the shore in this belt differs markedly at different points 
about the harbor. On the Spit, and on parts of the east and west sides of the 
harbor, there is, at this level, a rather steep, well-drained, sandy or gravelly 
beach from 3 to 5 meters in width. At some points along the east and west 
sides and across the south end of the harbor this belt of the shore has a more 
gentle slope, a mucky soil, and is decidedly marshy. In the latter region 
especially there is a border 40 to 60 meters in width that is nearly flat. In 
spite of this marked difference in the character of the littoral region, many of 
the dominant plants found at these levels are shared in common by both the 
gravelly and marshy shores. Aside from those parts of the shore influenced by 
fresh water, the upper littoral beach and the upper littoral marsh have in com- 
mon, also, many of the less abundant plants. Because so many of these plants 
may occur on any sort of substratum, we shall discuss the vegetation of the belt 
as a whole, though occasionally speaking of “ beach” and “ marsh” to distin- 
guish a particular kind of substratum. For the sake of simplicity and clearness 
in presentation we will, however, discuss separately the seed plants and alge of 
this belt. 
A. SEED PLANTS OF THE UPPER LITTORAL BELT. (ASSOCIATIONS OF 
SPARTINA PATENS, SUA4IDA, SALICORNIA, JUNCUS, OR SCIRPUS.) 
The whole natural shore of the harbor for some distance below 6.5 feet is, 
as we have seen, completely dominated by a nearly continuous stand of a 
single grass, Spartina glabra. The only other seed plants found in that belt 
are Itleopsis and a few stragglers from the belt above. Algee of many species 
occur scattered through the Spartina, but, either because of their sparseness 
or of their small size, they are relatively inconspicuous. 
_ In the belt we are now to discuss, that lying between the 6.5 and 8 foot levels, 
no such uniformity of the plant covering is found. The character of the vegeta- 
tion here may differ greatly and sharply in immediately adjoining portions of 
the beach, where only very slight differences are apparent in the character of the 
substratum. 
The dominant plant in any one portion of the upper littoral beach or marsh 
may be any one of eight species of seed plants. In some places there may be a 
