18 MICHIGAN SURVEY, 1908. 



channel contained a gi'owth of ValUsneria spiralis, PotamoffCton oiispis,. 

 and the banks supported a growth of sedges, Lycopodium complanatum, 

 Clintonia horealis, alders and Mountain Ash. The surface of the, delta 

 Is strewn with driftwood and other plant remains, upon a clean sandy 

 bottom. Nearer the shore, upon a muddy bottom, were found an abund- 

 ance of Amphipod crustaceans, Eyalella knickerlockeri, Gammerus 

 'liiinuKnis, and the small bivalve molluscs, Pisidium. The fresh water 

 sponge, Spongilla lacmtris, was found here, and water striders, Gerris 

 remigis, were found on the surface. Individuals were abundant, so that 

 the fauna is relatively varied. 



Substation 6 included the southwestern coves of the Harbor. The 

 bottom was rocky, and covered in places with much sand; the water was 

 shallow and contained, near the shore, many patches of rushes, Scirpus 

 and Equisetum. Anodonta (jrandis footiana, Limnaea staynalis and 

 Pisidium were the characteristic molluscs, and a few fish were found. 



The protected character of the shore is noteworthy, . as no beach is 

 developed, b.ecause the coves are protected from the heavy lake waves. 

 Another characteristic feature is the sand bottom. This sand is carried 

 toward the head of the Harbor by the currents. Even at higher Lake 

 levels, this Harbor was sandy, as is shown by the sand banks on the 

 north shore, and these are being 're-worked by currents and waves 

 and carried up the Harbor. The spit developing from the south 

 shore. Fig. 17, illustrates this. 



Station III, Substations 4 and 5. Sumner Lake and Trail. The trail 

 to Sumner Lake (III, 4), begins on the south shore of Rock Harbor 

 and extends south about one-half mile to Sumner Lake. It passes 

 through a second growth of Birch and Aspen (which has followed a 

 burn), a small Arbor Yitae swamp, over a rock ridge to the north, shore 

 of the lake, where there are a few large Norway Pines, from 12 to 

 15 inches in diameter, and a few White Pines. But little attention was 

 given to the life along the trail, although a few observations on the bird 

 life were made, and some mammals were trapped. However, Sumner 

 Lake proved to be such an interesting locality that attention was given to 

 it more especially than to the trail. This lake has many of the charac- 

 teristics of a large lily pond, because the White Waterlilies and Pota- 

 mogetons form such a wide belt around the lake. Figs. 18-23. In pass- 

 ing from the interior of the lake toward the shore, the following zones 

 of vegetation are found: The bulrush zone, which is well developed, 

 with its denser growth about the eastern end; then the Yellow Water- 

 lilies, followed by the dense sedge zone which produces a substratum. 

 In the eastern and western ends of the lake the water gradually shal- 

 lows; but on the sides the change is more abrupt, thus interrupting- 

 the shallow water zone of sedges, as shown on the north shore, 

 Fig. 23. This encroachment of vegetation upon each end of the Jake 

 is very marked, and is much more extensive at the eastern end, 

 where the lake is drained into the head of Conglomerate Bay by a small 

 brook. The encroachment at the western end of the lake is well shown 

 in Fig. 19. A partial view of the eastern end of tlie lake is given in Fig^ 

 18. The sedge zone contains a variety of plants, including several or- 

 chids, Iris, Pitcher Plants, Buckbean, scattered Eriophorum and .Sphag- 

 num, Cassandra and Andromeda. The substratum is quaking and sinks 



