20 MICHIGAN SURVEY, 1908. 



time of 50° F.), were many species of Limnaea catascopitim and a 

 few adult Physa. Algae were only seen in the crevices. 



Station IV, Substations 1 and 2. Rock Pools and Scovill Point. 

 Scovill Point is an almost bare, glacially planed, narrow and low rock 

 ridge, projecting out into the lake. Nimierous small faults occur on 

 the sloping southern side, and these, supplemented by the waves, etc., 

 have produced rock pools. In one case a long row of pools occurred 

 along the line of the fault. The presence of tadpoles about an inch 

 long would suggest that these pools have some duration. The higher 

 summer waves might also reach many of these pools. Water striders, 

 Gerris, are abundant upon the surface, and a large deep ravine, near 

 the lake level, contained Sticklebacks, but no shells were observed in any 

 of these pools. 



Station IV, Suhstation 3. Bayou East of the Monuinent Rock Trail. 

 This is a very small pond which is connected with the Harbor by 

 a small stream just large enough to admit a row boat. It illustrates the 

 last stage of separation of the valleys from the Hai"bor, as only a very 

 slight fall of the lake level would completely isolate it. In this particular 

 case the outlet is on the south side, and not at one end as is usually 

 the case. The central part of the pond is open water and is surrounded 

 by an almost complete zone of Yellow Waterlilies, and a sedge zone con- 

 taining several low shrubs. The Waterlilies were badly infested by a 

 small leaf beetle, Galerucella, nymphaea; larvae, pupae, and freshly 

 emerged beetles were taken. A few dead shells of Anodoiita marginata 

 and one of Limnaea megasoma (the only specimen taken upon the 

 island) were secured here. An extensive suspended flocculent mud cov- 

 ered the bottom, so that molluscs could not obtain a foothold. At the west- 

 ern end of this pond innumerable small tadpoles formed an almost 

 compact pavement upon the bottom at the edge of the water. A few 

 dragonflies were seen, but were not captured. 



Station IV, Siibstation Jf, 8 and. 9. Forest on the Greenstone Range. 

 These three stations are combined because they are related to the forest 

 occupying the Greenstone range. The trail to Monument Rock (IV, 4) 

 begins on the north shore of Tobin Harbor and extends northwest about 

 one-half mile to Monument Rock. The forest is dense and is apparently 

 a second growth of Balsam, White Spruce, Birch and Aspen, with un- 

 derbrush* of Mountain Alder, Mountain Ash, Ground Hemlock, and a 

 ground cover of Few-flowered Cranberry, Glintonia 'borealis, Linnea 

 borealis, and Wild Sarsaparilla. In the moist places was found Ground 

 Cornel, Aster macrophyllus, an Equisetum. Lycopodium, and, in .wet 

 places of the swamp traversed, the Buckbean and Skunk Cabbage. For 

 some distance on the slope down from the base of Monument Rock occur 

 large blocks which are covered by a dense mat of mosses, and the 

 ground is covered with a thick layer of humus, so that the general 

 appearance of the vegetation is that of a mesophytic forest. 



The trail up the Greenstone (lY, 8), begins at the mouth of a small 

 brook at the head of Tobin Harbor, and follows the crest of an open 

 burned over ridge southeast for about half a mile. This ridge contains 

 a scanty growth of Amelanchier oligocarpa and alnifolia, Prunus penn- 

 sylvanica, Jack Pine, wild rose, Solidago, Bearberry and Yarrow. From 

 the end of this ridge a valley crosses to the north and contains large 



