BAKER: FIELDBOOK OF ILLINOIS LAND SNAILS 19 



origin. The white-lipped snail mentioned previously is known as 

 Polygyra albolabris (Say). The first name, Polygyra^ which 

 happens to be of Greek origin, indicates the genus to which the 

 snail belongs; the second, albolabris^ which is of Latin origin, 

 denotes the species. The word in parentheses is the last name 

 of the man, Thomas Say, who first described this species. His 

 name is in parentheses because this snail is no longer in the 

 genus in which he placed it. Originally, Say gave this snail the 

 name albolabris and placed it in the genus Helix. It was then 

 known as Helix albolabris Say. Later, when other scientists 

 decided that the species albolabris should be removed from the 

 genus Helix and placed in the genus Polygyra^ the name of the 

 original describer was included in parentheses, and the snail 

 then became known as it is today: Polygyra albolabris (Say). 



Not all species of snails have names ot Greek or Latin 

 origin. Vertigo morsei Sterki was named for Edward S. Morse; 

 Polygyra fosteri F. C. Baker, for Thural Dale Foster; Gastrocopta 

 holzingeri (Sterki), tor John M. Holzinger. It is not uncommon 

 for conchologists wishing to honor tellow scientists or friends 

 to give a Latinized form of their names to new species of snails. 



Our system of classification is known as the binomial or 

 two-name system and was first used definitely by the great 

 Swedish naturalist Linne, or Linnaeus, in the year 1758. The 

 system has been formally adopted, and no names published 

 previous to this date are now used bv students of the natural 

 sciences. 



Most present dav workers in the Mollusca have extended 

 the binomial system to include recognizable differences occurring 

 within species. Subtorms are designated by a third or variety 

 name. The species Polxgxra albolabris is divided into a number 

 of forms or varieties. The tvpical form is known as Polygyra 

 albolabris albolabris. Other Illinois forms of this species given 

 distinguishing variety names are known as Polygyra albolabris 

 dentata and Polxgxra albolabris alleni. 



Reasons for scientific names. — Many people ask why we do 

 not use common English names for snails as we do tor birds and 

 mammals. We mav answer that there are so many different 

 species of snails which resemble each other closely that it would 

 not be practical to give each a common name. Many scientific 

 names are not more difficult to pronounce or understand than 

 are some ot the names in common use which have been taken 

 from the Latin and Greek languages. For example, we speak 



