1913] COOPER—ISLE ROYALE 219 
deposit reaches the surface. Frequently the first invaders are stools 
of sedge or rootstocks of Nymphaea and Calla which have been 
washed out from some eroding portion of the shore. 
It may thus be seen how the plant life supplements the physio- 
graphic processes. Upon one bank the current may be steadily 
destroying the vegetation (grasses, shrubs, and even trees); while 
on the other, where deposition is in progress, the same types are 
being developed through the normal course of the swamp succession. 
Note should be made of the peculiarly rich aquatic flora which 
inhabits the shallows of this and similar sluggish streams. The 
list of species obtained in the several localities of this type includes 
the following of special interest: Nymphaea advena Ait., Vallisneria 
spiralis L., Utricularia vulgaris L. var. americana Gray, U. inter- 
media Hayne, U. minor L., Myriophyllum verticillatum L. var. 
pectinatum Wallr., M. spicatum L., M. alterniflorum DC, Potamo- 
geton natans L., P. alpinus Balbis, P. amplifolius Tuckerm., P. 
heterophylius Schreb., P. heterophyllus {. terrestris Schlecht., P. 
praelongus Wulf., P. perfoliatus L., P. zosterifolius Schumacher, 
P. obtusifolius Mertens and Koch, P. filiformis Pers., Callitriche 
palustris L., Castalia tetragona (Georgi) Lawson, Bidens Beckii Torr., 
Scirpus subterminalis Torr., Sparganium diversifolium Graebner, 
S. minimum Fries, Sagittaria latifolia Willd. f. hastata (Pursh) 
Robinson, S. cuneata Sheldon, Lemna trisulca L., Ceratophyllum 
demersum L., Hippuris vulgaris L., Glyceria borealis (Nash) Batchel- 
der, Calla palustris L., Isoetes macrospora Dur. Though not a 
plant, Spongilla should “ mentioned as an important element in the 
aquatic life. 
At the head of Duncan Bay there are two delta swamps, both 
smaller than the one just described. One of these was studied with 
care, and the locality is included here because the swamp forest is 
well developed. Fraxinus nigra is the pioneer, and is present, but 
not abundant, in the mature forest. Thuja comes next and is the 
most important species. Larix, Picea canadensis, Abies, and 
Betula alba var. papyrifera, in order of abundance as named, com- 
plete the list. In passing toward the shoreward edge of the swamp 
forest Larix is the first to disappear. Thuja holds out much longer, 
and the ground is covered in places with tangles of layered branches 
