ECOLOGY OP NORTHERN MICHIGAN. 51 



gyratus. A conspicuous feature of the bogs in this region is the lack of un- 

 dergrowth. As may be seen from the list of species, the forms that com- 

 pose the undergrowth consist only of a few herbaceous forms, which is 

 in striking contrast to the density of the undergrowth in the surrounding 

 forest. 



Station VII. Lake Desor. This lake lies between the Greenstone and 

 Minong Trap Ranges. Its shores are for the most part shelving and covered 

 with a fine silt-like deposit. The islands, however, have uniformly rocky 

 shores. The coniferous forest of the slopes comes down to the margin of 

 the lake where it grades into a narrow zone of Hoary Alder, Viburnum 

 opulus and Arbor Vitae that lines the shores. The aquatic flora and fauna is 

 very poor. The marginal forms consist of the plants, Equisetum sp., Phragmites 

 communis, Sparganium eurycarpum, and occasionally the White Water Lily 

 (Castalia odorata); the frog, Rana sylvatica cantabrigensis, and the molluscs, 

 Planorbis bicarinatus striatus, and Anodonta marginata. On the rocky 

 shores of the islands, the vegetation consists of a scattered growth of 

 Isoetes sp. and Phragmites communis in the water among the rocks, and 

 Equisetum arvense on the. rocks in exposed places. The animals collected 

 here are the leeches, Haemopis grandis Verrill and Nephelopsis obscura 

 Verrill, a number of caddis fly larvae, and the molluscs, Planorbis hirsutus, 

 P. exacuous and parvus, and Physa sp. 



Station VIII. Siskowit Bay. The only part of Siskowit Bay worked 

 was the west end in T. 64 N., R. 32 W. The shore at this point consists of 

 outcropping strata of conglomerate that dip under the bay, and are often 

 broken up into shingle beaches. Owing to the grinding of the waves, there 

 is practically no aquatic life, although a small, Physa is sometimes found 

 on the larger rocks. In the pools that occur occasionally along this beach 

 behind the outcropping strata, the conditions are more favorable. Small 

 mats of Algae may occur on the rocks and there is a limited fauna of which 

 caddis fly larvae, and molluscs, Physa sp. and Valvata sincera levrisii, are 

 the principal forms. The beach flora is also very limited, consisting chiefly 

 of Juneberry, Phegopteris polypodiales, Euthamia graminifolia, Campanu- 

 laria rotundifolia and Listera convallariodes that occur in the rock crevices 

 and scattered over the shingle beach. 



Station IX. Southwestern End of Minong Trap Range. As may be seen 

 on the map, the Minong Trap Range on Section 30, T. 64 N., R. 39 W. pro- 

 jects into Lake Superior, becoming deeply submerged several hundred yards 

 fromthe mainland. It is also sloping on the south side, owing to the dip of the 

 strata, but on the north side it is precipitous. Near the outer end of the 

 ridge, there are a number of rock pools in the angular spaces formed by the 

 removal of portions of the rock between the joint planes. These are very 

 similar in form and probably in origin to the beach pools in the Porcupine 

 Mountains. The flora of these pools is very limited, but a number of animal 

 forms are found such as the molluscs, Limnaea sumassi and Planorbis parvus, 

 the water strider, Gerris remigis, and caddis-fly larvae. The flora on the outer 

 end of the ridge consists of scattered patches of Parmelia conspersa, and a 

 crevice vegetation of Sibbaldiopsis tridentata and Dasiphora fruticosa Cam- 

 panularia rotundifolia, Solidago sp., Arbor Vitae and several grasses. 



Toward shore a thin soil covers the rock and supports a flora of Reindeer 

 Lichen (Cladonia rangifefina) , and the heaths, Bearberry, Dwarf Blue- 

 berry- and New Jersey Tea that are often found growing on the remains 

 of lichen mats. Here also are found Empetrum nigrum, and Lycopodium 

 annotinum, clavatum and complanatum. The first tree is the Arbor Vitae 



