MICHIGAN ACADEMY OF SCIENCE. 27 



was mucky bottomed and was covered with patches of white and yellow 

 water-lillies ; the lagoon itself was choked with such plants as Scirpus ameri- 

 canus, Hypericum virginicum, DuUchium arundinaceum, Lobelia cardinalis, 

 Eupatorium perfoUaturn, and a few, short-stemmed plants of Castalia odorata, 

 while at one end there was a considerable growth of Myrica gale. 



Primary species. 



Planorbis hicarinatus, var. approaching portagensis Baker; shelf form. In- 

 frequent. 



Campeloma decisum (Say). Infrequent; young. 



Lymnaea stagnalis perampla Walker. Very rare; young specimens. 



Secondary species. 



Amnicola limosa (Say). Abundant. 



Planorbis bicarinatus, var.; juvenile. Quite common. 



"Pisidium, juvenile, apparently regidare Prime." ^ Quite common. 

 - Planorbis hirsutus Gould. Quite common. 



Planorbis deflectus Say. Infrequent; dead shells. 



Musculium. securis (Prime). Infrequent. 



Physa ancillaria parkeri (Currier); juvenile. Very infrequent. 



Pisidium sargenti Sterki. One specimen; "not typical." 



3. Swamp Point Lagoon. (Map 2, d; no separate map). On Swamp 

 Point, the sand spit had surrounded the lagoon to a greater extent than at 

 Hook Point; there was only a channel, a few centimeters deep, connecting 

 it with the main lake in 1911; and this was also filled in by the growing 

 spit during the summer of 1913, so that it was only open during very high 

 water. The bottom of the shelf nearby was more or less mucky and there 

 was a considerable development of the weed zones, which reached very close 

 to shore on account of the exceptional narrowness of the shelf in this portion 

 of the lake. The bottom of the lagoon was also covered with marly muck, 

 but this deposit was thicker and was also mixed with decayed and matted 

 rushes and other plant remains. This lagoon closely approximated a pond, 

 both in fauna and flora. Some of the prominent plants were Spartina 

 michauxiana, Scirpus validus, Phragmites communis, Scirpus americanus, 

 Potentilla palustris, Lobelia kalmii, and Rosa Carolina. 



Primary species. 



Campeloma decisum (Say). Infrequent; young specimens. 



Secondary species. 



Musculium securis (Prime). Quite common. 



Segmentina crassilabris Walker. Quite common. 



Lymnaea obrussa Say. Infrequent; young specimens. 



Pisidium sargenti Sterki. A few young specimens, "small and slight." 



Planorbis bicarinatus, var.; juvenile. Rare. 



Planorbis sp. Rare; juvenile, too young to be identified. 



Physa ancillaria parkeri (Currier), juvenile. Rare. 



4- Sedge Point Pool. (Map 2, e; map 9). At Stony Point, somewhat 

 over a hundred yards west of Sedge Point, a steep, stony bank sloped up 

 directly from the waters edge to a height of from fifteen to twent}^ feet. 

 This "sea-cliff" showed signs of considerable, recent erosion at the base, 

 while to the east of it a long ridge became apparent; the whole of the latter 

 had apparently been formed as a sand spit from the sand worn away from 



'The pisidia were indentified by Dr. V. Sterki, and the notes in quotation marks were made by 

 him. 



