214 TERRESTRIAL AIR-BREATHING MOLLUSKS. 



• » 



ment higher than wide, subrectangular. The whole upper margin is broadly- 

 reflected. The reflection is very short, and bears three short stout cusps, the 

 central the longest, each cusp bearing (I presume) a distinct cutting point. 

 The central tooth, in those species whose dentition is known to me, is as large 

 as the laterals, antl not smaller, as seems to be the rule in our species of Pupa. 

 The lateral teeth are like the centrals, but asymmetrical. The reflected 

 portion is small, tricusj)id, or bicuspid. The marginals are wide, low, with a 

 broad, irregular denticulated reflection. 



Shell dextral. 



Subgenus ISTHMIA, Gray. 



Vertigo Gouldi, Binney. 

 Vol. III. n. LXXI. Fig. 2. 



Shell light chestnut, cylindrical ovate ; whorls rather more than 4, ventri- 

 cose, the last occupying nearly one half the length of the axis ; aperture lateral, 

 composed of two unequal curves meeting in the centre of the peristome, with 

 five prominent, white teeth, namely, one upon the transverse margin, two upon 

 the umbilical margin, and two upon the labial margin ; peristome thickened, 

 not reflected; umbilicus a little open. Length, 2 mill.; diameter, 1 mill.; aper- 

 ture, § mill. long. 



Pupa Gouldii, Binney, Proc. Bost. Soc. Nat. Hist., I. 105 (1843) ; Terr. Moll., 

 II. 332, PI. LXXI. Fig. 2. —Gould, Bost. Journ. Nat. Hist., IV. 352, PI. 

 XVI. Fig. 9 (1843). — Pfeiffer, Mon. Hel. Viv., II. 358 ; KifsTER in Chem- 

 nitz, ed. 2, 124, PI. XVI. Figs. 20 - 23. 

 Vertigo Gouldii, Stimpson, Shells of N. E., 53 (no descr.). — W. G. Binney, Terr. 

 Moll., IV. 148; L. & Fr.-W. Sh., I. 250 (1869). — Tryon, Am. Journ. 

 Conch., III. 309 (1868). —Gould and Binney, Inv., 440, Fig. 701 (1870). — 

 Morse, Amer. Nat., I. 669, Fig. 60 (1868). 

 Isthmia Gouldii, Morse, Journ. Portl. Soc, I. 38, Fig. 95, PI. X. Fig. 96 (1864). 

 From Maryland through New England. It therefore belongs to the Northern 

 Region, extending along the Appalachians into the Interior Region. 



Animal with no tentacles ; black above, foot gray, tapering posteriorly, and 

 rounded at the extremity ; carries the shell at an angle of about forty-five 



degrees. 



Fig. 119. Jaw scarcely arcuate, of equal size 



throughout, ends rounded, anterior sur- 

 face with longitudinal lines and trans- 

 verse stria? ; concave margin simple, no 

 median projection. 



Lino-ual membrane with 75 rows, each 



Lingual dentition of rerttVo GouWt (Morse). rOW containing 23(11 — 1 — 11) short 



and stout teeth, 7 perfect laterals. Cen- 

 trals tricuspid ; laterals bicuspid ; marginals serrated. 



It has been referred to V. Alpestris, Aid. by Gwyn Jeff*reys, 1872, p. 246, 

 An. Mas:. Nat. Hist. 





