140 THE NAUTILUS. 



cies mentioned above have been differentiated. This diagram ex- 

 presses roughly the relationships of the species and varieties: 



subpalliata- 



palliata 



obstricta 



carolinensis 



I 

 sargentiana appressa — perigrapta 



? 

 dentifera. , 



Polygyra appressa Say. 



Surface striate, but having no spiral incised microscopic lines ; 

 outer lip frequently having an upper tooth, or the indication of it ; 

 parietal tooth generally long, curving downward and nearly joining 

 the columellar lip. 



This species was collected by Say on Long's Expedition. It is 

 abundant in Illinois, Arkansas, Missouri, etc. Say's types are lost, 

 but his description unmistakably indicates this form. 



Polygyra appressa perigrapta Pils. 



Surface striate and having crowded microscopic spiral incised 

 lines, especially beneath ; outer lip with no upper tooth ; parietal 

 tooth short, not connecting with columella. 



Distribution mainly southern ; Woodville, Ala. ; Cherokee Co., N. 

 C. ; Columbus, Ga. ; etc. The types are Woodville specimens. 



Polygyra fallax Say. 



This is, as the writer has elsewhere shown, the H. introjerens of 

 Bland. It is not i\iQ fallax of all modern writers and collectors. 



Polygyra fallax obsoleta Pils. 



General features as in the type, but all teeth of the aperture much 

 reduced in size, the upper lip tooth nearly or wholly obsolete. New- 

 bern, N. C. 



Polygyra tridentata edentilabris Pils. 



General characters as in the type, but lip teeth wanting in per- 

 fectly mature examples. 



