28 SIXTEENTH REPORT. 



Stony Point and other places along the shore. Ice had apparently assisted 

 in building this spit. 



Behind this ridge were a series of swamps and ponds, beginning with areas 

 of damp, low ground near Stony Point, and terminating in the large pond 

 shown on the map of Sedge Point (Map 9). Beyond Sedge Point, as can 

 be seen from the map, a submerged continuation of the spit extended out 

 towards Pine Point, and this was apparently separating a new pool. The 

 bottom of the shelf on the outer side of this latter portion of the spit was 

 quite sandy and unprotected, but the bottom behind it was covered with a 

 considerable deposit of marl. 



The Sedge Point Pool was mucky-bottomed and the water had a reddish 

 tinge, probably due to iron. The center of the pond was free from vegeta- 

 tion, except for a gew scattering potamogetons, but around the dege was a 

 more or less complete zone of water plants. This was dominated by Scirpus 

 validus, intermixed with water-lilies, along the inner shores, and by Scirpus 

 americanus along the outer and eastern edges. In the shallow water, espe- 

 cially along these latter shores, was a thick growth of such plants as Hyper- 

 icum virginicum, Dulichium arundinaceum, Proserpinacea palustris, Lobelia 

 cardinalis, Eupatorium perfoliatum, and Sium cicutaefolium. At the western 

 end the bottom was very mucky and was dominated by such plants as 

 Phragmites communis and Typha latifolia. It was in the shallow water 

 around the eastern end, where the mucky layer was least prominent, that 

 most of the shells were found. 



Clams. 

 Anodonta grandis footiana (Lea). Very rare; in the central, weedless area. 

 Lampsilis nasuta (Say). Very rare; ditto preceding. 



Primary species. 



Lymnaea stagnalis appressa (Say), rarely somewhat approaching perampla 

 Walker. Very abundant, but usually not very large. One of the largest 

 measured: altitude 41.9 mm., diameter 21.2 mm., aperture length 23.1 mm. 



Planoi'bis trivolvis Say. Infrequent; shells quite small and flat. The 

 largest specimen measured: greater diameter 18.6 mm., lesser diameter 15.5 

 mm., altitude of aperture 7.1 mm. 



Lymnaea exilis Lea. Apparently infrequent. The largest specimen ob- 

 tained measured: altitude 36.7 mm, diameter 11.7 mm., length of aperture 

 16.7 mm. 



Planorbis campanulatus smithii Baker. Only dead shells obtained. 



