ALG OF UPPER LITTORAL BELT 91 
From the two lists just given it will be seen that, aside from Ascophyllum, 
Fucus, or Bostrychia, in occasional tufts and Hildenbrandia incrusting the 
pebbles of fresh-water streams, the alge of this belt are Schizophycee or 
Chlorophycee. 
The felts and mats of alge found on the upper littoral levels of the Marsh 
and those of the west shore, though similar in general character, are somewhat 
different in make-up, and, in the commoner constituent species, from the felts 
and coats of the sandy shore of the Spit. On the soft and constantly wet mud, 
on the bases of seed plants growing on the Marsh, and on many wet spots on 
the west shore, the alge form in some places loose dark or light green turfs or 
mats, composed usually of several species. In other places green or gelatinous 
blackish blots occur which are often made up of a single species, nearly pure. 
On the sandy or gravelly better-drained beaches of the Spit, though loose mats 
are not entirely wanting, the alge present are more often arranged in dense felts 
over the firm mud or sand and in the furrows between the pebbles. Others may 
form compact leathery or slightly spongy, dull blackish incrustations over the 
projecting surfaces of the pebbles of the beach (plate xB). The first type of 
association, the tangles or felts on sand or mud, are scattered quite generally 
along the whole south shore of the Spit, between the 6-foot and 7.5 or 8 foot 
levels, but chiefly between 6.5 and 7 feet. On sunny days, the firmer of these 
felts on the more sandy mud of the beach dry out and crack into numerous small 
polygonal sheets, several centimeters across and a millimeter thick. These curl 
up at the edges and may peel off sufficiently from the substratum to be floated 
to a new locality at the rise of the tide. Associations of the second type referred 
to, the dense incrustations on pebbles, or more rarely on shells, simply dry, 
during low tide, to thin, hard coats, adhering tenaciously to the surfaces of the 
pebbles. The tangles or mats found about the bases of the seed plants of this 
shore are looser and more like those found on the Marsh and on the west shore. 
These dry out to curly or cobweb-like tangles hanging loosely about the stems of 
their supports. 
The distribution of the tangles, turfs, felts, and crusts of alge on the Spit 
has been fairly constant during the several years our study has been in progress. 
Detailed notes made in 1908 and 1910 show essentially the same distribution of 
the various types of association of the alge of this belt. It is as follows: 
Beginning at 1,000 west we find rather sparse loose felts on sandy mud beside 
the footpath among Spartina patens, etc., at 7.5 to 7.75 feet. These felts are 
made up chiefly of Lyngbya, Microcoleus, and Oscillaria, but with considerable 
Rhizoclonium and some Vaucheria. From here on eastward to 800 west, we 
find the soil covered with a thin felt from which Rhizoclonium and Vaucheria 
have about disappeared, while Calothrix is more abundant than farther west, 
forming a blackish coat on pebbles. From this point eastward to 670 west, 
the felt is sparse, and chiefly of Lyngbya, Microcoleus, and some Rhizoclonium 
near the 6.5-foot level. From 670 west eastward to 560 west there is a con- 
siderably denser felt, chiefly of these same Schizophycez, on the soil of the areas 
dominated by Salicornia and Sueda, and certain intermittent areas of the 
pebbly beach have black incrustations of Calothriz, etc. From 560 west to 430 
west thin felts of these same Cyanophycee are found only on shaded soil between 
6.25 and 7 feet, and crusts occur on the sides of some pebbles in the shade of 
Sueda or Spartina. Rhizoclonium is found here but infrequently at these 
