132 TERRESTRIAL AIR-BREATHING MOLLUSKS. 



Zonites significans, BLAND. 



Shell umbilicate, depressed, discoidal, thin, with fine irregular strias, which 

 are almost obsolete at the base, shining, pale horn-colored ; spire little elevated ; 

 Fig 48 suture slightly impressed ; whorls 6, subplanulate, the last roundly 

 inflated, rather flat at the base, excavated around the umbilicus, 

 which is pervious, and equal almost to one fifth of the diameter 

 / "~\ of the shell ; aperture oblique, depressed, lunate ; peristome sim- 

 f & D pie, acute. Greater diameter 4i, lesser 4 mill. ; height, 2 mill. 



\ ' Helix significans, BLAND, Am. Journ. Conch., II. No. 4, p. 372, 



|Z.1ife!ii> PL XXI. Fig. 9 (1866). 



Gastrodonta significans, TRYON, Am. Journ. Conch., II. 163 (1866). 

 Hyalina significans, W. G. BINNEY, L. & Fr.-W. Sh., I. (1869). 



Fort Gibson, Indian Territory ; Union County, Tennessee. I consider it a 

 species of the Cumberland Subregion, with the western range shared by many 

 of the species of the subregion. 



In a young specimen of significans, having 4 whorls only, there are 3 small 

 teeth, one by itself, and at some distance from it 2 others, situated as the 

 teeth are in multidentata. Whether these teeth are or not constant in the 

 antepenultimate whorl of significans, I am unable to determine. It is especially 

 allied to Z. multidenlatus, from which it differs in being of larger size with 

 wider umbilicus (Bland). 



Jaw not observed. 



Lingual membrane (PL III. Fig. R) ; 16 1 16 teeth, with 2 perfect laterals. 



Genitalia not observed. 



Zonites internus, SAY. 

 Vol. III. PL XXX. Fig. 4. 



Shell very narrowly perforated, depressed, slightly convex ; epidermis red- 

 dish-brown, shining ; whorls 8, with regular, equidistant, elevated, oblique, 

 rounded ribs, separated by distinct grooves ; suture deeply impressed ; aper- 

 ture flattened, transverse, narrow ; peristome thin, acute, thickened internally ; 

 within the base of the aperture, somewhat distant from the margin, are 2 

 prominent, sub-lamelliform, white teeth, not reaching the edge of the peri- 

 stome ; base smooth, polished, umbilical region indented. Greater diameter, 

 5 mill. : height, 3j mill. 



Helix interna, SAY, Journ. Acad., II. 155(1822); BINNEY'S ed. 18. BINNEY, 

 Bost. Journ. Nat. Hist., III. 405, PL XXI. Fig. 1 (1840) ; Terr. Moll., II. 

 247, PL XXX. Fig. 4. DEKAY, N. Y. Moll. 46 (1843). CHEMNITZ, 2d ed., 

 I. 200, Tab. CI. Figs. 1-4. PFEIFFER, Mon. Hel. Viv., I. 183. REEVE, 

 Con. Icon. 718. W. G. BINNEY, Terr. Moll., IV. 121. 



Helix pomum-adami, GREEN, DOUGHTY'S Cab., III. 35 (1834). 



Gastrodonta interna, TRYON, Am. Journ. Conch., II. 258 (1866). 



Hyalina interna, W. G. BIXXEY, L. & Fr.-W. Sh., I. 49, Fig. 79 (1869). 



