ALGA? OF UPPER LITTORAL BELT 97 
the same level (2,480 north by 800 west). It is worthy of note that these alge, 
which push up higher than any others, in fact to levels where they are not 
immersed in salt water for days at a time, nevertheless always avoid fresh water. 
Whenever these alge occur near fresh-water rivulets they are always found just 
above the level of the water flowing when the tide is out. 
One species of Ulothriz, probably U. implexa Kiitz. has been found in this 
belt at two points on the eastern side, near the 7-foot line, where wet much of 
the time by fresh water (1,010 north by 1,060 east). 
Vaucheria thuretu (or V. piloboloides var. compacta Collins) is of far less 
frequent occurrence here than in the belt below, but it does push up into this 
belt even as far as 7.5 feet at certain places on the Marsh (near 100 south by 
1,150 east) and along the shaded western shore. At 1,714 north on this latter 
shore there is a patch over a square meter in area at 7 to 7.5 feet. This alga, 
like several others noted above, avoids prolonged immersion in absolutely fresh 
water, though it is frequently found in the neighborhood of fresh rivulets, on 
soil kept moist by them. 
PHHOPHYCER, 
There are no brown alge that are truly characteristic of the upper littoral 
belt. Only two of these from the belt below (Ascophyllum nodosum and Fucus 
vesiculosus) ever get up above the 6.5-foot level. Of these, Ascophyllum only 
rarely even reaches to that level on the natural shores, as, e. g., at 1,440 north 
on the west shore, where it was found attached to stones on the bottom. On the 
wharves, however, as was noted in speaking of the rockweed association of the 
belt below, small plants of Ascophyllum may develop as high as the 7-foot level 
in protected places. 
Fucus vesiculosus is likewise rare above 6.5 feet, except on the wharves, 
where, on northern walls, or on the north side of piles, it may occur at the 
%-foot level or slightly higher. 'T'wo varieties of this species (var. spiralis and 
var. laterifructus) sometimes get up from their characteristic habitat in the 
belt below to the 7-foot level on the shore of the Spit. Nowhere do these rock- 
weeds occur in such numbers as to appreciably affect the character of the vegeta- 
tion of the shore in this belt. A possible reason for this is a general lack on the 
natural shores of stones and shells to which the plants might attach themselves. 
It would seem as if other favoring conditions, such as light, flooding by salt 
water, and high moisture-content of the surrounding air, must be present here 
to quite as adequate a degree as on the wharves. 
RHODOPHYCEA. 
As is indicated by our list, only two species of red alge push up into this 
upper littoral belt. These are Bostrychia rwularis and Hildenbrandia proto- 
typus, and each is found at these higher levels only where the conditions are 
somewhat exceptional. 
-_ Bostrychia has been found as high as 7 or 7.25 feet, but when found at this 
height it is in protected cracks in the stones, piles, or logs of the wharves, or 
more rarely (950 north by 970 east) on stones in the shade of seed plants, on 
pebbly shores. This protection from the sun and evaporation is evidently a 
decided advantage to a plant that is not reached by the high waters of several 
successive tides in the intervals between the fortnightly spring tides. The 
