HELIX. 



119 



Helix isopnomostomos, y, Gmelin (teste Pfeiffer). 



Tridopsis hiisuta, Woodward, Man. pi. xii, f. 7, no desc. 



Helix fraterna, Wood, Index Suppl. 21, pi. viii, f. 16 (1828) ; ed. Hanley, 



226, f. 16. 

 ? Helix porcina, Say, Long's Exped. (1824), II, 257, pi. xv, f. 2 (young) ; 



Binney's ed. 30, pi. Ixxiv, f. 2.— DeKay, N. Y. Moll. 45 (1843).— 



Pfeiffer, Mon. Hel. Viv. Ill, 97.— Bland, Ann. N. Y. Lye. VI, 344, 



with fig. (1858). 

 Stenotrema hirsuta, Tkyon, Am. Journ. Conch. Ill, 57, pi. ix, f. 24 (1867). 



From New England to Kansas and Virginia. Also in the post- 

 pleiocene beds of the INIississippi Valley. 



The last whirl in front of the aperture, especially in the larger 

 forms, is more or less angulated, but never carinated. The 

 position of the parietal tooth is often rather oblique, but usually 

 nearly parallel with the peristome, and is more or less distant 

 from it. The nature of the epidermis varies ; in some forms the 

 hairs are very numerous, in others comparatively few. Spiral 

 impressed lines sometimes occur beneath the epidermis, at the 

 base of the shell. 



The central teeth of the lingual membrane are tricuspid, the 



Lingual dentition of Melix hirsuta. 



side cusps very small ; the laterals of same shape, but bicuspid ; 

 uucini irregularly toothed. 



Helix maxillata, Gould. — Shell imperforate, globose-conic, rather 

 solid, completely covered with short hairs, chestnut-colored ; spire convex- 

 conoid, apex obtuse ; whirls five, rather convex, gradually increasing, the 

 last anteriorly deflected, constricted, subinflated below ; aperture obliquci 



