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HELICODISCIJS, Morse. 

 1. Helicodiscus lineata, Say. 



Plate 4, figure GO. 



Discoidal, greenisli -yellow; whorls 4, visible 'below as well 

 as above, with numerous parallel revolving lines, suture well 

 impressed; aperture narroAvlunate; base shallow-concave; a 

 pair of teeth within the outer lip, remote from the margin, 

 and another pair further within and visible through the trans- 

 lucent periphery, in each pair one being placed above, the 

 other below it. 



Diam. 3 mill. ^v,Ty:Q3r.",!P,,,/ ".S'.C'' 



Maine to Yirgiuia, westwards to Ohio, Texas. 



PSEUDOHYALINA, Morse. 



"" Diam. = 5 mill. 



1. Pseudohyalina limatula, Ward. 



Plate 4, figure Go. 



Almost planorboid; whorls 4|, increasing regularly, well 

 roundexl; suture very distinctly impressed; aperture small, al- 

 most round ; umbilicus rather large, as wide as the last whorl, 

 well defined and deep. Color very light, nearly white. 



Diam. 5 mill. 



New York, Ohio, Indiana, Michigan. Coll'^'' O:-'^- 



""* Diam. = 2| mill. 

 2. Pseudohyalina minuscula, Binney. 



Plate 4, figure 62. 

 Whorls 4, depressed, whitish, slowly increasing in diameter; 

 suture deep ; aperture sub-rotund; umbilicus large and deep. 

 Diam. 2, — 2 J mill. Gc:i.>V,G.i'/; ' ^- ' 



United States east of Rocky Mountains, from Maine to 

 Florida, and West Indies. 



