PLANT ASSOCIATIONS ahy) 
higher belt, where these associations have a somewhat different make-up. On 
stony substrata within the limits of this belt, which are confined practically to 
the walls of the wharves, we find a nearly continuous rockweed association. This 
is dominated by Fucus vesiculosus, F’. evanescens, and Ascophyllum nodosum, 
but it embraces also a considerable number of smaller alge of all classes, many 
of them very numerous. A few of the latter are found on the fringing marsh 
also, but most of them are not. 
(4) The upper littoral belt extends from 6.5 feet to 8 feet. On gravelly, 
well-drained portions of the shore this level is usually dominated by Salicornia 
or Sueda, and less frequently by Spartina patens, often mixed with Distichls. 
These are the areas that we have called “upper littoral beach.” On flat, 
poorly-drained shore with peat-like soil we find an upper littoral marsh 
dominated by Spartina patens, by Distichlis spicata, or by Juncus Gerardi. 
Where the soil is more or less saturated with fresh water Scirpus americanus 
dominates. This apparently corresponds in most respects to the “ salt- 
meadow ” of Warming. 
(5) The supra-littoral belt of vegetation extends from high-water level at 
8 feet upward as far as the direct influence of the sea is felt by the vegetation, 
which is often 10 feet and on the Spit up to 12 feet. In this belt also we find 
two distinct associations, determined by the character of the soil, especially by 
its drainage. In sandy, well-drained portions, which are found only on the 
Spit, we find a supra-littoral beach, or storm beach, dominated by Ammophila 
arenaria, with which are associated three or four prominent species of dico- 
tyledons and a score of other species, chiefly seed plants, of less frequent 
occurrence. On flat, undrained portions of the shore between these levels, where 
the peaty soil is subjected to submergence by spring tides, and is in many places 
kept continually moist by subterranean fresh water, we have a supra-littoral 
marsh, the “ higher littoral marsh” of Warming. This sort of marsh is well- 
developed only at the head of the harbor. Near the 8-foot level the soil-water 
is brackish or nearly salt, while near the upper limit of this marsh at the 9-foot 
level the soil-water is practically fresh, at least during the growing-season. 
In consequence, evidently, of this difference in salinity, and in other soil 
characters, as well as in elevation, the vegetation differs greatly in different 
parts of the marsh. The lower, more saline portions are dominated by Spartina 
patens or by Juncus Gerards, while fresher areas are characterized by Scirpus 
americanus, and the highest parts are occupied chiefly by Aspidium thelypteris. 
1. THE PLANKTON. 
The plant constituents of the plankton of the Inner Harbor consist of a 
relatively few species of diatoms of the genera Melosira and Navicula, and a few 
species of Peridinaces. Of the latter one species of Glenodinium often occurs in 
such numbers, over areas of scores of square meters, and to a depth of 0.5 meter 
or more, as to color the water a deep brown. This condition was frequently 
noted two or three times a summer, and often lasted for several successive days. 
Professor C. B. Davenport informs us that this or a similar species of the 
Peridines is sometimes so abundant in September as to kill many of the fish 
in the harbor by clogging their gills. The time at our disposal did not suffice 
for a detailed study of the plankton and its daily and seasonal variation. 
2 
