298 TERRESTRIAL AIR-BREATHING MOLLUSKS. 



Tennessee, Alabama, Georgia (near Columbus). A species of the Cumber- 

 land Subregion. 



This is another interesting example of the gradual transition, by almost im- 

 perceptible modifications, from one species to another, and of the many changes 

 which are wrought by the varied combination of a few characters signalizing a 

 group. However great its general resemblance to S. hirsutum may be, this 

 species is decidedly characterized by the singular jaw-like plate within the 

 fauces. 



Animal unobserved. 



Stenotrema monodon, Rackett. 



Vol. III. PI. XLI. 



Shell imperforate or umbilicated, globose-depressed, diaphanous, reddish 

 horn-colored, covered with short hairs ; spire rather convex ; whorls 5h, the 

 upper ones flattened, the two last convex, the last anteriorly gibbous, con- 

 stricted at the aperture, ; umbilicus more or less opened, or completely closed ; 

 aperture widely lunar, somewhat narrowed by a lamelliform tooth on the parie- 

 tal wall ; peristome acute, reflected, thickened with white callus within ; a 

 transverse internal tubercle on the base of the shell. Greater diameter 11, 

 lesser 10 mill. ; height, 6 mill. 



Helix monodon, Rackett, Linn. Trans., XIII. 42, PI. V. Fig. 2 (1822) ; ed. 

 Chenit, 269, PI. XXVII. Fig. 5. — Wood, Ind. Supplem., PI. VII. Fig. 15 

 (1828); ed. Hanley, 226, Fig. 15. — Binney, Bost. Joum. Nat. Hist., III. 

 360, PI. X. Fig. 1 (1840) ; Terr. Moll, II. 147, PL XLI. lower Figs. * — Gould, 

 Invertebrata, 174, Fig. 113 (1841). — Adams, Vermont Mollusca, 159(1842). — 

 W. G. Binney, Terr. Moll., IV. 60 ; L. & Fr.-W. Sh., I. 120 (1869). — Gould 

 & Binney, Inv. of Mass., ed. 2, 419 (1870). — DkKay, N. Y. Moll., 35, part, 

 excl. syn., PI. III. Fig. 19, not Fig. 21, a, b (1843). — Mrs. Gray, Fig. Moll. 

 An., PI. CXCIII. Fig. 11 (ex. Bost. Joum., no desc). — Billings, Cana- 

 dian Nat, II. 100 Fig. 6 (1857). —Morse, Amer. Nat., I. 151, Figs. 12, 13 

 (1867). — Pfeiffer, Mon. Hel. Viv., IV. 320. 



Helix convexa, Chemnitz, part (excl. syn., et tab. LXVI. Figs. 24, 27), PI. X. 

 17, 18. — Pfeiffer, Mon. Hel. Viv., III. 268 (excl. j3 et 7). — Deshayes in 

 Lam., VIII. 112 ; 3d ed., III. 308 ; Encycl. Meth., II. 253 (1830) ; in Fek. 

 1. c, I. 144. — Reeve, Con. Icon., 696 (1852), excl. syn. ; No. 717 (1854). 



Helicodonta hirsuta, o, Ferussac, Tabl. Syst., 101, no desc. 



Stenotrema monodon, Morse, Joum. Portl. Soc, I. 10, Fig. 13, PI. II. Fig. 2; 

 PI. IV. Fig. 14 (1864). — Tryon, Am. Journ. Conch., III. 56 (1867). 



VAR. FRATERNA. 



Helix fraternr , Say, Long's Exp., II. 257, PI. XV. Fig. 3; Binney's, ed. 30, 

 PI. LXXIV. Fig. 3. —Mrs. Gray, Fig. Moll. An., PI. CXCIII. Fig. 5, no 



l The specimen figured is abnormal in not having a parietal tooth. 



