23 



— diam. 21, alt. 10 mill.; umbilicus wide, spire some- 



what depressed, whorls somewhat angular at the 

 periphery; surface with fine, regular rib-striae; 

 with brown, irregular, radial mottlings. 



alternata, Say. 



12. Tebennophorus, Binn. carolinensis, Bosc. 



13. Pallifera, Morse. dorsalis, Binn. 



14. Vallonia, Risso. 



1 Surface finely striated; aperture lunar-circular. 2 



— surface ribbed; aperture almost circular 3 



2 last whorl not or little expanding toward the aper- 



ture; peristome well everted; umbilicus rather reg- 

 ular; diam. 2.5 mill. (Eu.) pulchella, Mull. 



— last whorl expanding toward the aperture; peris- 



tome little everted; umbilicus irregular, elongated; 

 spire smaller; suture less deep; diam. 2.3 mill.(Eu.) 



excentrica, Sterki. 



3 last whcrl descending to the aperture; diam. 2.3 



to 2.5 mill. (Eu.) costata, Mull. 



— last whorl not descending; diam. 2 mill. 



parvula, Sterki. 



15 Polygyra, (Say) Pils. 



I. Diam. 6 to 11 mill.; inside, at some distance above the 

 aperture, at the base and columellar wall, a lamella, 

 or tooth-like callus. 2 



— diam. 12 mill, or more; inside no such callus. 5 

 2 parietal tooth, high, complex, strongly connected 



with the ends of the peristome, which bears a 

 strong, white lip with two stout teeth directed in- 

 ward; spire much depressed; whorls 5^, the 

 last widely receding to the periphery below, de- 



