132 TERRESTRIAL AIR-BREATHING MOLLUSKS. 



Zonitea Bignificans, Bland. 



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



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



Fig. 48. suture slightly impressed ; whorls 6, subj)lanulate, the last roundly 



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



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



Oof the shell ; aperture obli(}ue, depressed, lunate ; peristome sim- 

 ple, acute. Greater diameter 4^, lesser 4 mill. ; height, 2 mill. 

 Helix signifcans, Bland, Am. Journ. Conch., II. No. 4, p. 372, 

 [Z.signifi. PI. 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 muUidentata. Whether these teeth are or not constant in the 

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

 allied to Z. multiden(atu>i, from which it differs in being of larger size with 

 wider umbilicus (Bland). 



Jaw not observed. 



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



Genitalia not observed. 



Zonites internus, Say. 

 Vol. III. PI. 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, 3| mill. 



Helix interna, Say, Journ. Acad., II. 155(1822); Binney's cd. 18. — Binney, 

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

 247, PI. 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 pomuin-adami, Green, Doughty's Cab., III. 35 (1834). 



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



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



