MOLLUSCA. 131 



Succinea retusa, S. avara, and Agriolimax campestris were found out on 

 the decaying sedges. 



8. Cove, almost cut off from Bay. On the south side of Sand Point 

 and about a mile from its base, there is a large cove that is separated 

 from Wild Fowl Bay, except for about ten rods, by a long sand spit 

 which runs out from the shore in a southeasterly direction. This spit 

 has been formed, apparently, by the sand being washed down along the 

 coast by the off-shore currents, and deposited to form a small point, 

 which has increased with continued deposition, so that a long sand strip 

 has been built up. To all appearances, this process is still going on as 

 there is a shoal for some distance out from the end of the spit, and the 

 end itself is a low sandbar, elevated but slightly above the water. Prob- 

 abh' in time there will be formed a lake, like the several that are along 

 this side of Sand Point, which were apparently formed in a similar man- 

 ner. (PL XIII b.) 



This cove (known locally as "The Bayou'") is oval in shape and is 

 quite large, being about three hundred yards long b}"" one hundred wide; 

 in places the water reaches a depth of six feet. Scirpus americanus, 

 Typha latifolia, Potamogeton natans, the common white and yellow 

 water-liUes {Castalia odorata and Nymphaea advena), bulrushes (Scirpus 

 validvs). and other water plants, gaining a footing here, have deposited 

 a layer of soft, peaty muck, reaching, in places, a depth of fom- or five 

 feet. Along the north and south shores, the bottom is more firm and 

 sandy; here there is a zone of Scirpus aiyieiicaiius off shore, with a zone 

 of Scirpus validus outside of that. The west and southwest shores are, 

 however, very soft and mucky, the sedges hai-ing grown out for some 

 distance from the shore, forming a floating marsh. There is a moderate- 

 sized patch of Typha latifolia separating this soft portion from the firmer 

 southern shore. The whole center of the cove is soft -bottomed and over 

 large patches is almost covered with the flat, floating leaves of Pota- 

 mogeton natans and the white and yellow water-lilies. 



Planorbis trivolvis, P. exacuous, and P. parvus occurred thruout this 

 habitat, but the remainder of the shells were more restricted. Amnicola 

 icalkeri, A. limosa; Ancylus parallelus, Lymnaea humilis, and Physa 

 heterostrapha were found only on the under side of lily-pads, etc., in 

 places where the bottom was mucky. Lymnaea reflexa and an obese 

 variation of that species, Physa gyrina, P.- sayii, Planorbis hirsutus, 

 Lymnaea palustris] and L. ohrussa, on the other hand, were found only 

 in localities where the bottom was hard and sandy, while Musculium 

 securis was collected both from the latter place, and from among sedges 

 where the bottom was very mucky. 



Habitats of the Sand Dune Lakes. — 9. Shallow lakes, north side of 

 Sa?hd Point. Near the end of Sand Point, just south of the outer dune 



