22 MICHIGAN SURVEY, 1908. 



below the surface. The young of L. stagnalis occurred with the Physa. 

 A specimen of Oordiiis aquaiicus was secured here. 



Station IV, Substation 7. Head of Tohin Harbor. A small brook 

 empties into the head of the Harbor, and its brown water brings into the 

 bay quantities of vegetable remains and flocculent debris. These cover 

 the bottom near the mouth of the stream, and although carefully ex- 

 amined, were found to be singularly free of animals. Upon patches of 

 Potamogeton perfoUatum occurred a few Physa, and in the shallow 

 water a few fish were found. (No. 35.) 



Station V. Siskotcit Bay, Lake, and Vicinity. This station includes 

 all the localities in the vicinity of Siskowit Bay and Siskowit Lake, ex- 

 cept that of VIII, '04, which is at the head of Siskowit Bay. 



Station V, Substation 1 and 3. The Bay Beach at Camp, and the 

 Rock Clearing. The beach (V, 1), is protected from the waves of the 

 open lake and bay by large off-shore islands. The rock composing it is 

 vesicular lava, and slopes 1o the water at an angle of about 10 degrees. 



The Eock Clearing about Camp (V, 3), begins at the beach and ex- 

 tends up the slope backward to the Balsam, Spruce and Birch forest as 

 a park-like opening. The soil, mainly of residual and humic origin, is 

 very shallow and completely lacking in places. The surface of the rock 

 is rough, showing that it has been eroded since glaciation. In places 

 the rocks are more or less covered by crustaceous and foliaceous lichens, 

 or, where there is more humus or soil, by Cladonia, Fig. 24. Where 

 the soil is deeper is found Bijarberry, Narrow-leaved Cow-wheat, Soli- 

 dago, grasses and moss. A scattered shrub growth is composed of 

 Juniperus nana and Amelanchier, Fig. 25 and 26, and the bordering 

 tree growth consists of Balsam, Black and White Spruce, Birch and 

 Arbor Vitae. In the shade of these bordering trees. Aster macrophyllus 

 develops in abundance. The above description also outlines the prob- 

 able succession of plant societies upOn this surface, all stages of which 

 are now to be found within this area. Many smaller patches of this 

 open condition are found scattered through the forest and are becoming 

 shaded and converted into the forest as a soil develops, Fig. 27. 



The fauna of the openings is rather characteristic and abundant. 

 Of course many species range over a variety of plant societies and only 

 recognize a clearing or forest society, and not their varieties. Yet 

 others are much more sensitive to smaller environmental units. This 

 is well shown by certain ants. Ant nests of Formica, fusca as illustrated 

 by Fig. 28, and certain spiders, as Pardosa, are quite characteristic of 

 the Cladonia-Bearberry plant society. The opening, as contrasted with 

 the forest, is frequented by grasshoppers, such as Melanoplus fasciatus; 

 butterflies, as Argynnis and Basilarchia arthemis; and the dragonflies, 

 Sympetrum, which were very abundant and characteristic {Aechna 

 patrols the margins of such openings). The robber fly, Asilus annulatiis, 

 frequents such open sunny areas where animal food abounds. 



TTie vertebrate frequenters of the open were the Flickers, which were 

 observed by McCreary to destroy ant nests. Several of such demolished 

 nests were seen. Toward night a nocturnal association frequented the 

 open; the bats on wing; and the hares came from the forest to feed, 

 having been in hiding during the day. 



No doubt the presence of this opening, in part, determined the location 



