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. hir.tutum may be, this 

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

 fauces. 



Animal unobserved. 



Stenotrema monodon, RACKETT. 

 Vol. HI. PL XLI. 



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

 horn-colored, covered with short hairs; spire rather convex; whorls 5i, 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, PL V. Fig. 2 (1822) ; ed. 

 CHENU, 269, PL XXVII. Fig. 5. WOOD, Ind. Supplem., PL VII. Fig. 15 

 (1828) ; ed. HANLEY, 226, Fig. 15. BINNEY, Bost. Journ. Nat. Hist., III. 

 360, PL X. Fig. 1 (1840) ; Terr. Moll., II. 147, PL XLI. lower Figs. 1 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). DEKAY, N. Y. Moll., 35, part, 

 excl. syn., PL III. Fig. 19, not Fig. 21, a, b (1843). MRS. GRAY, Fig. Moll. 

 An., PL CXCIII. Fig. 11 (ex. Bost. Journ., 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), PL X. 

 17 ( is. PFEIFFER, Mon. Hel. Viv., III. 268 (excl. /3 et 7). DESHAYES in 

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

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



Helicodonla Ursula, a, FERUSSAC, Tabl. Syst, 101, no desc. 



Slenotrema monodon, MORSE, Journ. Portl. Soc., I. 10, Fig. 13, PL II. Fig. 2 ; 

 PL IV. Fig. 14 (1864). TRYON, Am. Journ. Conch., III. 56 (1867). 



VAR. FRATERNA. 



Helix fratei-na, SAY, Long's Exp., II. 257, PL XV. Fig. 3; BINNEY'S, ed. 30, 

 PL LXXIV. Fig. 3. MRS. GRAY, Fig. Moll. An., PL CXCIII. Fig. 5, no 



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



