14 



ANALYTICAL KEYS FOR IDENTIFYING THE 

 LAND MOLLUSCA OF OHIO. 



BY DR. V. STERKI. 



The arrangement of the keys as offered here is some- 

 what different from the form commonly in use. But it is 

 expected that they will be found convenient after a little 

 practice. 



It has not been the intention of the writer to give full and 

 minute descriptions of every genus and species, but simply to 

 facilitate their identification. So the most obvious and strik- 

 ing features had to be used rather than the most scientific, 

 which should be consulted in special works on the subject. 

 Yet the descriptions are not quite so fragmentary as might 

 appear. If we go, from any given species, backward through 

 the numbers of the keys leading to it, the combined charac- 

 ters will, as a rule, make rather good diagnoses. 



For the examination of the small and minute forms, a 

 good loupe should be used; its aid, and close attention to 

 every paragrajih and word of the diagnoses will enable any- 

 one to identify even the species of Pupa, Vertigo, etc., com- 

 monly considered difiicult. 



Anatomic characters have, as a rule, been omitted, except 

 where they are essential features of a genus (as is the case 

 e. g. with Hyalinia and Zonitoides.) But even there, the 

 characters of the shells will be sufficient for identification. 



The descriptions are understood of mature and fresh spec- 

 imens; this is especially of value in regard to the apertural 

 parts, the color and transparency or opacity of the shell. 

 The dimensions given mean the average; in most species 

 the sizes are subject to considerable variation. 



In addition to the species actually known to inhabit our 

 territory, one has been admitted which is likely to be found 

 in its eastern and northern part: J 7/ ;'/?/« limfida Gld. 

 Other species may possibly have to be added to the list. 



