440 BOTANICAL GAZETTE [JUNE 
at the time, but these could not reach the surface, and the 
blossoms decayed without opening. Like the preceding species, 
this did not occur in the shallow water next the shore line. 
Gratiola aurea, in its strictly hydrophilous form, was found in 
company with these also, but did not appear to flourish. 
Between the zone of these three plants and the shore line 
was a space of open water, devoid of phanerogamic vegetation. 
On the shore line, its roots submerged, Euthamnia (Solidago) 
graminifolia appeared, and its rich border of bloom nearly cir- 
cuited the pond. That the zone of Limnanthemum and Lobelia 
did not extend inward till met by Euthamnia seemed a circum- 
stance needing explanation, especially since both the former 
- flourish elsewhere in very shallow water. 
At some points wave-marks on‘the bottom had been seen, 
and it was noticed that the outer limit of these coincided with 
the shoreward limit of the Limnanthemum zone. Sandy silt in 
some quantity was coming in from the surrounding slopes. 
Limnanthemum plants along the shoreward margin of the zone 
were” found buried in sand at the bottom, and dying. There 
seemed then reason for believing that the shoreward limit of this 
zone was set by the action in shallow water of the wavelets in 
"shifting the silt, and burying the bottom-growing vegetation. 
is a graphic illustration of action of this sort, drawn 
trom arge pond on an adjacent island, called West end lake. 
Silt is coming into the pond from the low surrounding hills. AL 
‘one spot a great bowlder, out from the shore line, breaks the 
wave ets, and the silt has run out to it as a sandy peninsula 
whose « curving sides represent the hy perbola of the broken wave 
tion. — Thus the outlying bowlder plays a rather fantastic - 
the growth of the land, and shelters a certain area from t 
peenne J ac ion of material which comes from the shore. The 
: ttom of the margin of this lake is due = 
low water vegetation is constantly over- 
of Juncus militaris is growing. the ee 
Eotenaia, nevertheless, gice v just at € oS 
caching silt. Sheltered behind the nce = 
