MOLLUSC A. 105 



The shells from the Bay were, as a rule, larger and heavier than 

 those from inland waters. 



64. Planorbis truncatus Miles. — Only two living specimens of this 

 species were oV)tained, but dead shells were quite common in places 

 along the exposed north shore of Sand Point. The two living speci- 

 mens, which were juvenile, were collected from floating driftwood and 

 dead sedges in a protected sedge marsh on the south shore of Sand 

 Point (7) near Turtle Bay. The dead shells had probably been washed 

 up from deep water (1), as continued search did not reveal any adult 

 specimens' anywhere. It seems probable that in this region the species 

 lives during the summer in deep water, and comes into shallow water 

 at certain seasons of the year to breed, etc., as has already been noted 

 in the case of Lynmaea mcgasoma. 



65. Planorbis campanulatus Say. — Typical specimens of this shell 

 were obtained from the ox-bow pond of the Pigeon River (22), on 

 Potamogeton, lily-pads, etc. 



Planorbis campanulatus, var. — Many of the specimens of this shell 

 are far from typical, the size being smaller and the whorls narrower, 

 the lips not so strongly campanulate, and the reflection more abrupt, 

 the end of the last whorl turning upward very much after the manner 

 of variety minor, which shell they somewhat resemble. A shell from 

 Sand Point measures: height 5mm., greater diameter 11.5mm., aper- 

 ture length 4.5mm., aperture width 3mm. 



This type of shell was obtained from the lakes on the south side of 

 Sand Point (10), and from the upper portion of the Pigeon River (23) 

 and the ox-bow pond off from it (22). A specimen was also found 

 washed up on the rocky east shore of Stony Island (2). Shells 

 nearer the average for campanulatus were collected from Stony Island 

 and Caseville, in the same localities as the more aberrant ones. In 

 the latter locahty typical shells were found, as mentioned above. 



66. Planorbis campanulatus, var. minor Currier. ^ — Dead shells of 

 this variety were found in large numbers in Rush Lake. These ap- 

 peared to be fresh shells, but no living specimens were found. An 

 individual measures: height 4.5mm., width 9.75mm., aperture length 

 4mm., aperture width 4.25mm. 



67. Planorbis exacuous Say. — This shell was obtained on drift- 

 wood in the sedge marshes (7), on driftwood and lily-pads in Turtle 

 Bay (8), on lily-pads and decaying leaves in the lakes (9, 10) and on 

 leaves in the perennial swamps (19), at Sand Point; on driftwood in 

 protected places along the shores, both rocky and sandy (4, 7), on 

 Stony Island; and on driftwood in the ox-bow pond of the Pigeon 

 River (22). The amount of carination varies considerably in these 

 shells. 



