1869.] 133 [Perkins. 



Neristoma Tryon, 1865. 



Neristoma columella Tryon, Am. Journ. Conch., Vol. I, 

 p. 248. Radix columella Morse, Journ. Port. Soc. Nat. Hist., Vol. 

 I, p. 42. Lymnceus columellus Say, Am. Conch., p. 65, 1821. Lym- 

 naza columella Gould, Invert. Mass., p. 215, fig. 144; Hald., Monogr., 

 p. 38, pi. xii ; do. var. chalybea, Gould, Invert. Mass., p. 216, fig. 145. 



PLANORBIDiE. 



Planorbis Guet, 1756. 



Planorbis lentus Say, Am. Conch., p. 210, pi. liv, fig. 1, 1834; 

 Gould, Invert. Mass., p. 202, fig. 132; Hald., Monogr., p. 18, pi. iii, 

 figs. 3-6 ; Binney, Shells of N. A., pt. n, p. 104, fig. 177. 



Common everywhere. 



Planorbella Hald., 1842. 



Planorbella campanulatus Binney, Shells of N. A., pt. n, p. 

 109, fig. 184. Planorbis campanulatus Say, Am. Conch., pp. 129, 

 164, 1821; Hald., Monogr., p. 9, pi. i, figs. 7-11; Gould, Invert. 

 Mass., p. 204, fig. 133. 



Not common. 



Menetus H. & A. Adams, 1853. 



Menetus exacutus Morse, Journ. Port. Soc. Nat. Hist., Vol. i, 

 p. 41; Binney, Shells of N. A., pt. n, p. 126, fig. 210. Planorbis 

 exacutus Say, Am. Conch., p. 64, 1821 ; Gould, Invert. Mass., p. 208, 

 fig. 137; Hald., Monogr., p. 21, pi. iv, figs. 1-3. 



Common in West River and Harris's Pond. 



Gyraulus Agassiz. 



Gyraulus defleetus Morse, Journ. Port. Soc. Nat. Hist., Vol. 

 i, p. 41; Binney, Shells of N. A., pt. n, p. 129, fig. 215. Planorbis 

 defleetus Say, Am. Conch., p. 128, pi. lxxiv, fig. 8, 1829; Hald., Mo- 

 nogr., p. 25, pi. iv, figs. 4-7; Gould, Invert. Mass., p. 207, fig. 136; 

 De Kay, Moll. N. Y., p. 65. 



Not very common. 



Gyraulus dilatatus Morse., Journ. Port. Soc. Nat. Hist,, Vol. 

 i, p. 41 ; Binney, Shells of N. A., pt. n, p. 131, fig. 218. Planorbis 



