POLYGYRA. 69 



p. 425, 1819 ; Enum. and Acct. etc., p. 3, 1831 (type Tr. lunula,= H. 

 tridentata Say). -\-Menomphis RAF., /. c. Xolotrem,a RAF., I. c., 

 (proposed for X. lunula, X. triodopsis and X. clausa, all undescribed 

 and unidentified). Odotropis, Chimotrema and Toxotrema RAF., 

 Jotirn. de Phys., t. c., p. 425 (y=Stenotrema). Stenotrema RAF., /. c.~ 

 (type S. convexa=H. stenotrema Fer.). Aplodon RAF., I. c. (type A. 

 nodosum ; undescribed and unidentified). Stenostoma RAF., Enum. 

 and Account, 1831 (type S. convexa Raf.). Mesodon RAF., /. c. 

 (type M. maculatum Raf., unidentified). Trophodon and Odomph- 

 ium RAF., 1. c. unidentified. Ulostoma ALBERS, Die Hel. 1850, p. 

 95 (=Polygyra s. str., Stenotrema, Triodopsis, etc. Not Ulostoma 

 TRYON!). Patera ALBERS, I. c., p. 96 (=Mesodon auct.). Cyclo- 

 doma SWAINS, (part), Malacol., p. 193. Tridopsis BECK, Index 

 Moll., p. 22 ; GRAY, P. Z. S. 1847, p. 173, type If. plicata. 

 Helicodonta (in part) FER., Prodrom., p. 33. Anchutoma (in part) 

 H. & A. AD., Gen. Rec. Moll, ii, p. 205, 1858. Angystoma (in part) 

 KLEIN, Tent. Meth. Ostr., p. 10, 1753 (pre-Linnsean). 



Neohelix v. IHERING, Zeitschr. f. Wissensch. Zool. liv, p. 482, 

 1892 (=Polygyra Pils.). 



Con/. W. G. BINNEY, Terr. Moll, v, and STREBEL & PfeflFer, 

 Mex. Land- u. Siisswasser-Moll. (anatomy). 



Shell helicoid, varying from globose or depressed-globose to lens- 

 shaped or planorboid, the periphery carinated or rounded ; umbilicus 

 either open or closed. Surface striated or hirsute ; corneous, yellow 

 or brown, generally unicolored, but sometimes with many bands, the 

 most constant being supra-peripheral, the others when present being 

 wholly indefinite in number and position. Lip well reflexed; aper- 

 ture typically obstructed by three teeth, one parietal, two upon the 

 lip ; but any or all teeth often wanting. 



Animal externally as in Helix, the mantle subcentral, foot rather 

 long and narrow, not distinctly tripartite below, and without longitu- 

 dinal grooves above the lateral margins, although a sort of foot- 

 margin is produced by the tessellated granulation of the edge. Sur- 

 face rather coarsely irregularly granulated, the granulation finer 

 posteriorly ; back with a pair of indistinct grooves extending from 

 mantle to facial area; sides of foot, and sides and top of tail without 

 any distinct oblique or longitudinal lines, irregularly granulated ; tail 

 rounded above, obtuse behind. Mantel edge reflexed to correspond 

 with the lip of the shell, its edge even ; shell lappets none ; body- 



