CONCHOLOGT. 105 



very short ; aperture large and oval ; colour pale yellowish 

 green. 



FAMILY VII. 



CoLiMACEA. Eleven genera. 

 1, Helix. The Snail. One hundred and seven species. 

 According to the systematic arrangement of Lamarck, 

 this genus now consists of shells with peculiar characteristic 

 distinctions. 



By Linnseus, marine, land, and fresh-water shells were 

 united in this genus, and so confounded that the naturalist 

 would often look in vain for the distinguishing characters 

 which would enable him to class and determine the genus 

 of the object under examination. 



Notwithstanding the divisions of Lamarck, its species are 

 numerous ; the shells are terrestrial, and found in all parts of 

 the globe ; some are rare and beautiful. 



The term Helix was given to this genus from the spiral 

 form of the shell. 



Shell extremely variable in form, generally globular, some- 

 times ventricose, conoid, never turriculated ; summit con- 

 stantly obtuse and rounded ; aperture generally of a medium 

 size, but sometimes very large or very small, always modi- 

 fied by the turn of the spire ; oval, semi-lunar, more wide 

 than long, edges disunited, entering but very little into the 

 formation of the interior ; the right lip or margin thickened 

 or reflected. 



Helix vesicalis. Helix mutata. 



H. algira. H. gigantea. 



H. pomatia. H. polyzonalis. 



H. aspersa. H. monozonahs. 



H. vermiculata. H. puUa. 



H. alonensis. H. versicolor. 



H. lineolata. H. Naticoides. 



H. picla. H. Madagascariensis. 



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