174 College of Forestry 



and polished and are unlike the young shells of warreniana. 

 They are doubtfully referred to heterostropha. 



68. Physa gyrina Say. Not collected in 1916. 



Family Ancylid^ 

 Genus Ancylus Geoffroy 



69. Ancylus parallelus Haldeman. 



This characteristic fresh-water limpet was collected from 

 all bottoms except boulder in water one and a half to ii feet 

 deep, the greater number occurring on a sandy clay bottom in 

 one and a half feet of water. In this locality it is associated 

 with filamentous algse {CEdogoniiun and Cladophora), but it is 

 usually more abundant on such plants as Nyniphcca, Castalia, 

 Typha, Scirpus, and Sparganium. 



70. Ancylus fuscus Adams. 



Young individuals of this limpet were found in one habitat 

 on a sandy clay bottom in one and a half feet of water. 



71. Ancylus tardus Say. Not collected in 1916. 



*72. Ancylus species. 



A single specimen (No. 73id) of Ancylus was found on a 

 boulder bottom in two and a half feet of water. It was sub- 

 mitted to Dr. Bryant Walker, who says of it : "I cannot be 

 sure of the species and therefore prefer to leave it with a 

 cjuestion until you can get more, which would be very desirable. 

 It does not seem to be an\- of the more common species." 



Family Planorbid.^ 

 Genus Planorbis Mialler 



73. Planorbis trivolvis Say. 



Specimens of typical trivolvis were found in but one habitat, 

 a quiet lagoon on a muddy bottom in one and a half feet of 

 water. 



74. Planorbis trivolvis fallax ilaldeman. 



This form of trivolvis, listed in the previous paper (Baker, 

 '16, p. 277), was again collected in 1916, on sand, boulder, 



