CLASSIFICATION OF HELICES. 



XXXVll 



would be intended. The following table simply shows the genera 

 arranged according to some of the more obvious shell characters. 

 I. Shell with lip thin and sharp, as in Zonites, not expanded, 

 reflexed or with a rib-like thickening within. 



1, American : a, no internal teeth or laminae : Pyramidula 42, 



Punctum 6, Amphidoxa 39, Hyalosagda 61, 

 Thysanophora 54, Zaphysema 65, Glyptos- 

 toma 192, Polymita 184. 



b, with internal teeth or laminae : Helicodiscus 

 51, Sagda 58. 



2, Old World : a, no internal laminae or teeth : Pyramidula, 



Punctum 6, Phrixgnathus 9, Flammulina 10, 

 Phasis 36, Charopa 22, Pararhytida 52, 

 Anoglypta 159, Gary odes 161, Panda 163, 

 Pupisoma 52, Acanthinula, Chalepotaxis 167. 

 b, with internal laminae or teeth : Atlantica 50, 



Laoma 8, Endodonta 20. 



II. Shell with lip blunt, hardly or not at all expanded, usually 

 thickened within. 



1, American : Polygyrella 78, Polymita 184. 



2, Old World : Pedinogyra 158, Leucochroa 232, Helicella 245, 



Geomitra 238, Hygromia 269, Acanthinula 

 280. 



III. Shell with lip expanded, not flatly reflexed. 



1, American : Praticolella 67, Polygyratia 81, Macrocyclis 



165, Thysanophora 54, Pleurodonte 84, Cepolis 

 177, Lysinoe 191, Epiphragmophora 193, Oxy- 

 chona 189, Vallonia 282, Solaropsis 166. 



2, Old World: Coxia 83, Dorcasia 172, Stylodonta 149, Heli- 



cophanta 151, Ampelita 155, Camsena 101, 

 Obba 107, Chloritis 117, Albersia 124, Thersi- 

 tes 125, Planispira 110, Papuina 136,Ganesella 

 168, and most genera of Belogona. 



IV. Shell with the lip decidedly reflexed, often toothed. 



1, American : Polygyra 68, Vallonia 282, Pleurodonte 84, 



Lysinoe 191. 



2, Old World : Acavus 153, Pyrochilus 154, Camama 101, Obba 



107, Chloritis 117, Thersites 125, Planispira 

 110, Papuina 136, Helicostyla 216, Chloraea 



