36 MICHIGAN SURVEY, 1905. 



Calopteryx aequabilis, Aeschna clepsydra and Plathemis lydia, and the 

 Kingfisher, Muskrat, etc. 



Station V. Substation 3. The biota of Carp Lake indicates that the 

 environmental conditions are very similar to those that exist in the river 

 above it but are even more pond-like. The fish are the same with the ex- 

 ception of the Horned Dace, which was not found here. The Sucker and 

 Yellow Perch seem to predominate. Toward the shore the bottom becomes 

 covered with vegetation, chiefly Myriophyllum, among the leaves of which, 

 especially in the axils, occur the snails, Amnicola limosa and Valvata tricar- 

 inata. This society soon becomes mixed with Potamogeton natans that forms 

 a large well defined zone. On the inner margin of this zone, the Tape Grass, 

 Vallisneria spiralis, often occurs in extensive mats but does not form a 

 definite zone. The next zone of importance is composed largely of the 

 Yellow Pond Lily that is replaced near shore by the Canada Rush, Juncus 

 canadensis, that becomes largely mixed in shallow water with the Scouring 

 Rush, Equisetum fluviatile. 



Station V. Substation 1. Where this marginal rush zone extends to the 

 shore, the bivalves, Sphaerium simile, Anodonta marginata, and Pisidium 

 sp., and the univalves, Planorbis bicarinatus, campanulatus and deflectus 

 are found in the silt and on the small stones. 



On the fine sand of the narrow beach, Equisetum hyemale associated with 

 the Horned Bladderwort (Utricularia cornuta), Nodding Ladies Tresses, 

 and Seven Angled Pipewort forms a scattered vegetation behind which 

 comes an alder thicket which is followed in turn by the mesophytic forest 

 types. 



Station V. Substation 2. The delta that is being formed by the river 

 at the east end of the lake is similar in many ways to the mud flats along 

 the river and presents similar but more extensive environmental conditions. 

 On the submerged part of the delta, Juncus canadensis is mostly absent 

 from the rush society which is extensive and composed principally of 

 Equisetum fluviatile associated on the inner margin with E. hyemale and 

 littorale. These forms are replaced on the area that is ordinarily unsub- 

 merged, by Dulichium arundinaceum, Car ex filiformis, riparia and viridula, 

 associated on the dryer areas with Calamagrostis canadensis, Scirpus cyperinus, 

 Agrostis hy emails, Eupatorium purpureum, Deschampsia flexusa, Panicularia 

 canadensis, Solidago uliginosa, Swamp Milkweed, Nodding Ladies Tresses, 

 Pale St. Johns wort and Marsh Cinquefoil. 



The fauna also shows the similarity between the conditions of this habitat 

 and the mud flats. The dragon flies found here are Enallagma hageni, 

 Nehalennia irene, Enallagma carunculatum, Ischnura verticalis, Hagenius 

 brevistylus, Gomphus spicatus, Aeschna clepsydra and Plathemis lydia 

 Of these Enallagma hageni is the characteristic form and occurs in consider- 

 able numbers. The birds, as on the mud flats, are the waders and shore 

 forms such as the Carolina Rail, Great Blue Heron, American Bittern, 

 Solitary Sandpiper and Wilson's Snipe. The nature of the habitat is also 

 shown by the presence of most of the amphibian species of the region. The 

 frogs are represented by Rana pipiens brachycephala, clamitans, and sep- 

 tentrionalis. No turtles were observed, but the Garter Snake, T. sirtalis 

 sirtalis was taken several times. 



The grass and sedge society passes directly into an alder society without 

 an intervening cassandra zone, and the forms of the alder society are in turn 

 followed by the forms of the deciduous forest. 



It was shown in the discussion of the topography that the tendency of an 



