( 45 ) 



GENUS HELIX. (1) FERUSSAC 



SUB-GENERA. 

 A. Horizontally volute, 



1. Helicogena. Fer. 



Globulous or elliptical ; Umbilicus masked . 

 peristoma simple. 



a Collumellatae. Columella solid and twisted. PI. 7, fig. 7, 8. 



b Acavse. Umbilicus entirely covered by an expansion of the columella, 

 PI. 7, fig. 11,14. 



c Perforata?. Umbilicus appearing in part, like a cleft, behind the expan- 

 sion of the columella. PI. 7, fig. 9, 10. 

 d Imperforatae. Depressed, umbilicus closed. PI. 7, fig. 15, 16, 18. 



2. Helicodonta. Fer. 



More or less globulous Mouth generally tooth- 

 and depressed ; peristoma ed in the perfect state, 

 reflected or thickened. 



a Personatae. Peristoma sinuous and thick ; or reflected with teeth, plates, 

 or folds. PI. 7, fig. 17. 



b Lamellatae. Mouth with one or more elongated internal plates. PI. 7, 

 fig. 19, «, 6, c, d, e. 



c Maxillatae. Peristoma with large teeth ; a gutter at the base of the co- 

 lumella. PI. 7, fig. 21. 



d Anostomse. Tomogeres, Montf. Mouth reversed or dorsal, with elevated 

 folds or teeth. PI. 7 y fig. 20. 



e Impressae. Inner lip with longitudinal elevated folds. PI. 1 , fig. 23. 



3. Helicigona. Fer. Ca- 



racolla. Lam. 



Carinated, sometimes 

 conical. 



a Caracollae. Umbilicus covered. PI. 7, fig. 22; pi. 8, fig. 1, 2. 

 b Vortices, Ockcn. Umbilicus masked or visible. PI. 8, fig. 3. 



4. Helicella. Fer. Vor- 



tex. Ocken. 



Elliptical or flattened. Umbilicus exposed. 



a Lomastoma?. Peristoma reflected. PI. 8, fig. 8. 

 b Aplostomae. Peristoma simple. PI. 8, fig. 4. 

 c Marglnatac. Peristoma margined. PI. 8, fig, 5, 7, 18. 

 (1) Vide p. 30. 



