Our British Snails 25 



two exceptions in British molluscs) have not. 

 Here again we must trace our snail down to the 

 sub-order of Pulmonata, or lung or air-sac breathers 

 as distinct from its sisters which inhabit water 

 and breathe by gills. This sub-order is again 

 divided into various families, Arion, Limax, 

 Testacella, Vitrina, Zonites, Helix, etc., and 

 Helix again is divided into various genera, 

 of which Helix is one, and even this is sub- 

 divided into sub-genera, Patula, Punctum, Acan- 

 thinula, Vallonia, Chilotrema, Gonostoma, 

 Pomatia, Tachea, etc., and to the sub-genus 

 Pomatia our garden snail as well as the " Roman 

 snail " belongs. Looking backwards we, therefore, 

 place our friend as the species aspersa, of the 

 sub-genus Pomatia, of the genus Helix, of the 

 family Helicidce, of the sub-order Pulmonata, 

 of the order Inoperculata, of the sub-class Gastero- 

 poda, of the class Cephala, of the sub-kingdom 

 of Mollusca, of the kingdom Invertebrata or 

 backboneless animals. 



It belongs by origin not to the earliest form 

 of snail, but to the most highly organized group 

 in the world, especially characteristic of the 

 European region, and possessing in their superi- 

 ority the power to colonize and dispossess 

 the original native snails of other lands. The 

 shell is globular in form with five whorls (the 

 Greek word ''helix" means a coil), each usually 

 marked with five bands of pigment. It is mainly 



