130 



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



FEK0SSAC, Tab. Syst. 38 ; Hist. pi. li, f. 3.— Wood, Ind. Supplem. 



21, pi. vii, f. 2 (1828) ; ed. Hanley, 226, f. 11.— Deshayes, Encycl. 



Meth. II, 213 (1830) ; in Lam. VIII, 115 ; ed. 3, 309 ; in Fer. /. c. 



I, 72.— BiNNEY, Bost. Journ. Nat, Hist. Ill, 382, pi. xvii (1840), 



part; in Terr. Moll. II, 183, pi. xxvii.— DeKay, N. Y. Moll. 28, pi. 



ii, f. 7 (1843).— Adams, Vermont Mollusca, 160 (1842).— Godld, 



luvertebrata, 173, f. 115 (1841).— Pfeiffek, Mou. Hel. Viv. 1,412; 



in Chemnitz, 2d ed. I, 84, pi. x, f. 7, 8.— Potiez et Michaud, Gal. I, 



114. — Mrs. Gray, Fig. Moll. An. pi. ccxci, f. 3 (ex Bost. Journ., no 



descr.).— Reeve, Con. Icon. no. 690 (1852).— W. G. Binney, Terr. 



Moll. IV, 70.— Bland, Ann. N. Y. Lye. VII, 423.— Morse, Amer. 



Nat. I, 150, f. 8, 9 (1867). 

 Triodopsis lunula, Rafinesque, En. and Ace. 3 ; ed. Binney and Tkyon, 68. 

 Triodopsis tridenlata, Tryon, Am. Journ. Conch. Ill, 50, pi. ix, f. 6, 13 



(1867). 

 Lister, pi. xeii, f. 92. 



Fig. 219. From Canada through all eastern N'orth America. 



One of the specimens figured is unusually large. 

 A curious pathological specimen, with a double 

 peristome, is here figured. 



The lingual membrane is broad ; central teeth 

 long, conical, with an acutely pointed apex ; laterals 

 of the same shape, but with a small side-cusp ; uncini with long 

 irregular denticles. 



Fig. 220. 



Helix tridenlata, 

 deformed. 





Lingual dentition of Helix tridentata. [Leidy.] 



Helix mullani, Bland. — Shell with umbilicus partially covered, 

 globose-depressed, dark horn-colored, irregularly striated, having a thin 

 epidermis with microscopic spiral lines, and tubercles (the latter with 

 hairs?); beneath the epidermis shining; spire short; whirls five and a 

 half to six, convex, the last gibbous above, scarcely descending, the base 

 rather smooth, much constricted at the aperture ; aperture subtriangular, 

 oblique, with a short, white, linguiform, parietal tooth ; peristome white, 



