102 LAND AND FRESH- WATER SHELLS OP N. A. [PART I. 



obtuse denticle on the right margin. Greater diam. 8, lesser 7 ; height 

 3^ mill. 



Polygyra dorfeuilliana, Lea, Trans. Am. Phil. Soc. VI, 107, pi. xxiv, f. 



118 ; Obs. II, 107 (1839) ; Troschel's Arch. f. Nat. 1839, II, 222. 

 Helix dorfeuilliana, Bla.nd, Ann. N. Y. Lye. (1858), VI, 294, pi. ix, f. 



24-26.— W. G. BiNNEY, Terr. Moll. IV, 86, pi. Ixxviii, f. 2, 14, not 



of Pfeiffer, Deshayes, Chemnitz, Reeve. 

 Eelix faiigiata, Binney, Bost. Journ. Nat. Hist. Ill, 388 (ikO) ; Terr. 



Moll. II, 193 (excl. descr., syn., and fig.). 

 Helix troostiana, var. ? Pfeiffer, Mon. Hel. Viv. Ill, 318, no descr. 

 Dcedalochila dorfeuilliana, Tbyon, Am. Journ. Conch. Ill, 66, pi. x, f. 20, 



21 (1867). 



Washington County, Texas ; Washita Springs, Ark. ; Coosa 

 River, Ala. ; Kentucliy, opposite Cincinnati. It thus appears 

 much more widely distributed than the allied species. 



H. dorfeuilliana differs materially in its characters from the 

 allied species ; the striae on the upper surface are not so well 

 defined as in troostiana, but more so than in hazardi, while the 

 base is more smooth than in either of them, having only very 

 delicate striae, with microscopic impressed spiral lines. The 

 parietal tooth is quadrate — the two teeth on the peristome are 

 more nearly of ^e same size and form than in fastigans and 

 troostiana. In this species the inferior tooth is transverse, and 

 in some specimens broader than the superior one, but has a some- 

 what pointed apex ; both are very nearly equally deeply seated, 

 but so far apart as to allow a view between them into the aper- 

 ture, leaving, as Mr. Lea expresses it, "to appearance three 

 nearly square apertures." Say would have described the two 

 teeth as "separated by a remarkable sinus." The peristome of 

 this is more thickened and less reflected than in the other species ; 

 behind it is deeply constricted, without any appearance of pits 

 showing the position of the teeth within. 



There is a form of H. dorfeuilliana which differs from the 

 type in that the superior tooth on the peristome is larger and 

 more deeply seated than the inferior one, and that the latter, 

 though more developed, is much of the same form as the inferior 

 tooth in fastigans and troostiana. The parietal tooth partakes 

 of the general character of that in Lea's type of dorfeuilliana, 

 but its lower and terminal margins project more perpendicularly 

 from the parietal wall. The umbilical perforation is also larger, 

 and the base of the shell is more smooth. The following are the 



