POLYGYRA. 279 



more convex, inflated below, constricted behind the peristome, descending at 

 the aperture, below with a grooved rimation of 1^ whorls, ending in a very 

 small umbilicus ; aperture oblique, subreniform, contracted, far within fur- 

 nished with a deeply seated, erect tubercle on the base of the last whorl ; 

 peristome white, very much thickened, not reflected, contin- 

 uous, its terminations but slightly approached, joined by a Fig. 178. 

 heavy, excavated, subquadrate callus projecting across the 

 aperture, the columellar margin with a deeply seated, trans- 

 verse, somewhat pointed denticle, distinctly separated from 

 a broader, equally deeply seated obtuse denticle on the right 

 margin. Greater diameter 8, lesser 7 mill.: height, 3^ mill. < . -^ » - 



Polygi/ra Dorfeuilliana, Lea, Trans. Am. Philo. Soc, VI. 107, P. Dorfeuilliana, 



PI. XXIV. Fig. 118 ; Obs. II. 107 (1839) ; Troschel's Arch. enlarged. 



f. Nat,, 1839, II. 222. 

 Helix Dorfeuilliana, Bland, Ann. N. Y. Lye. (1858), VI. 294, PL IX. Figs. 



24-26. — W. G. Binney, Terr. Moll., IV. 86, PI. LXXVIII. Figs. 2, 14; L. 



& Fr.-W. Sh., I. 101, not of Pfeiffer, Deshayes, Chemnitz, Reeve. 

 Helix fatigiata, Binney, Bost. Journ. Nat. Hist., III. 388 (1840); Terr. Moll., 



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

 Helix Troostiana, var. ? Pfeiffer, Mon. Hel. Viv., III. 318, no descr. 

 Dccdalochila Dorfeuilliana, Tryon, Am. Journ. Conch., III. 66 (1867). 



"Washington County, Texas ; Washita Springs, Arkansas ; Coosa River, Ala- 

 bama ; Kentucky, opposite Cincinnati. It thus appears much more widely 

 distributed than the allied species, perhaps enough so to be considered a spe- 

 cies of the Interior Region. 



Mr. J. G. Anthony obtained from Mr. Dorfeuille some facts concerning the 

 original discovery of this species, which prove beyond all doubt that it was 

 accidentally brought from Kentucky. It is not an inhabitant of Ohio. 



P. Dorfeuilliana differs materially in its characters from the allied species ; 

 the stria? 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, hav- 

 ing only very delicate stria?, with microscopic impressed spiral lines. The pa- 

 rietal tooth is quadrate — the two teeth on the peristome are more nearly of the 

 same size and form than in fastirjans and Troostiana. In this species the in- 

 ferior tooth is transverse, and in some specimens broader than the superior 

 one, but has a somewhat pointed apex ; both are very nearly equally deeply 

 seated, but so far apart as to allow a view between them into the aperture, 

 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 show- 

 ing the position of the teeth within. 



There is a form of Dorfeuilliana which differs from the type in that the 



