38 MICHIGAN SURVEY, 1905. 



is undoubtedly being filled up, and the present environmental and biotic 

 conditions are being changed toward those of the river flood-plain. 



Station IV. South of Carp Lake the country is covered by the biota of 

 the deciduous forest type which is essentially the same as on the north 

 slope. The small spring brooks which drain the region, however, bring in 

 a different set of conditions, and may be considered as representative of 

 the headwater conditions of the larger streams. The two studied on Sections 

 23 and 28, T. 51 N., R. 43 W., are shallow, cold, swift flowing streams from 

 6 to 15 feet wide with a bottom composed of gravel and stones. The biota 

 is limited in variety probably owing principally to the coldness of the water. 

 There is practically no aquatic vegetation, and the fauna consists chiefly 

 of the snail, Planorbis parvus, caddis and stone-fly larvae, and the frogs, 

 Rana septentrionalis, clamitans, and R. sylvatica cantabrigensis. On the 

 banks of these streams, however, the conditions are much more favorable. 

 The deciduous trees usually overtop them entirely, so that the humus con- 

 ditions along the margin are essentially the same as in the forest with the 

 exception of a considerable increase in the moisture content. The flora 

 that lines the creek is composed of such forms as Caltha palustris, Equisetum 

 sylvaticum, Cinna latifolia, Onoclea sensibilis, Scirpus cyperinus, Osmunda 

 claytoniana, Skunk Cabbage, Carex crinita and pubescens, and large mats of 

 Conecephalus conicus and Endocarpon miniatum. Behind this narrow zone 

 occur occasional clumps of alders (Alnus incand), and Mountain Maple. 



The molluscan fauna of the creek bank is characterized principally by an 

 increase in the abundance of the forest forms, while among very wet leaves 

 Physa sayii is occasionally found. 



It will be noticed that the biota of the creek bank is composed of members 

 of the alder, sedge and forest societies of the river valley, but that the forms 

 of the cassandra and coniferous societies are apparently lacking. 



Station VII. Practically the same conditions prevail in Little Carp Lake 

 as in Carp Lake, although its smaller size probably affects the biota to some ex- 

 tent. The deciduous forest forms extend down the sides of the bordering hills 

 nearly to the waters edge. Between the forest and the water there is a narrow 

 zone of vegetation the most conspicuous form of which is the Hoary Alder 

 (Alnus incand) which is associated with the Few Flowering Cranberry, etc. The 

 rush society in the margin of the water and on the delta (which is mostly 

 submerged) is composed principally of Equisetum (fluviatile where examined) 

 but for a short distance along the south shore the Canada Rush becomes 

 prominent. As a rule, the aquatic societies are not extensive, the vegeta- 

 tion of the rush societies is scattered even on the delta, while the pond lily 

 zone is only occasionally present. 



The bivalve, Anodonta marginata,is quite commonly found about the margin 

 of the lake, especially on the delta. The most characteristic fish, at this 

 time of the year, are the Sucker and Horned Dace, the latter being very 

 abundant. 



Station VII. Substation 2. Above the lake, Little Carp river is a small 

 meandering stream about 15 feet wide and 2 feet deep. It enters the lake 

 through a narrow valley about one-fourth of a mile long which is crossed 

 at the east end by several beaver dams. Above these dams, the valley widens 

 out into an amphitheater about a mile long by one-fourth mile wide. In 

 the narrow part of the valley near the lake, the space between the river and 

 the foot of the adjacent ridges is occupied by a dense thicket of Hoary Alder, 

 (Alnus incand). As the valley widens out above the dams, this alder zone, 

 composed now of the Hoary Alder, Betula glandulosa, and several willows, is 



