70 



ZONITIDAE 



Vitrea viridulus, is common under logs 

 and loose bark in some of the large 

 Illinois river valleys and their adjoin- 

 ing ravines. The distribution is spo- 

 radic. 



RETINELLA WHEATLEYI 



(Bland) 



The yellowish, glassy shell of Ret- 

 inella ivheatleyi, fig. B, less than one- 

 fourth inch (5 mm.) in diameter, is 

 wider than that of Retinella electrina 

 in proportion to its height and has a 

 more depressed spire, a flatter base 

 and a wider umbilicus. The umbilicus 

 is peculiarly expanded, causing it to 

 be elliptical, in contrast to the round 

 umbilicus in electrina. 



The species wheatleyi is found in 

 much the same habitats as electrina ; 

 rarely in woodlands bordering agricul- 

 tural lands. In Illinois it appears to 

 be confined to the southern half. 



RETINELLA RHOADSI 

 (Pilsbry) 



The yellowish shell of Retinella 

 rhoadsi, fig. C, less than one-fourth 

 inch (4 mm.) in diameter, may be 

 known from that of Retinella elec- 

 trina, which it resembles, by the fact 

 that its impressed, radiating lines, 

 which are especially well developed on 

 the upper surface, are widely and 

 regularly spaced, resembling those of 

 the shell of Retinella indentata. 



In Illinois, rhoadsi is known only 

 from the south end of Fountain Bluff 

 in Jackson County. 



