74 



ZONITIDAE 



One of the surprises of the 1932 

 molluscan survey of Illinois was the 

 discovery of the supposedly southern 

 species, Paravitrea capsella. This spe- 

 cies had not been reported from Illi- 

 nois previously, its nearest recorded 

 localities being Fayette County, Ken- 

 tucky, and Posey County, Indiana. It 

 is now known from seven counties in 

 Illinois, and the Natural History Mu- 

 seum of the University of Illinois con- 

 tains specimens from Jefferson and 

 Parke counties, Indiana. That this 

 species has been in Illinois for a long 

 time is evidenced by its discovery in 



Pleistocene deposits of early Wisconsin age in Stony Creek, 



near Muncie, Vermilion County, Illinois. 



PARAVITREA SIGNIFICANS (Bland) 



The shell of Paravitrea significans is similar in size, color 

 and general appearance to that of Paravitrea capsella. measuring 

 less than one-fourth inch (5 mm.) in diameter. It may be 



distinguished from the capsella shell 

 by its peculiarly flattened and concave 

 base, and the position of the periphery 

 of the body whorl, which is placed well 

 below the middle of the whorl, causing 

 the aperture to be strikingly diagonal 

 to the vertical plane of the shell. In 

 significans the spire is somewhat high- 

 er than in capsella. In these two spe- 

 cies half-grown shells are more diffi- 

 cult to distinguish than are mature 

 shells. Young shells of significans usu- 

 ally have one or two pairs of small 

 denticles which show through the shell 

 as white spots, illustrated in the small 

 figure. 



More common than capsella, but with similar habitats, sig- 

 nificans also is confined, in Illinois, to the state's southern half. 



