38 BULLETIN OF THE 



parietal tooth ; peristome narrow, scarcely reflected, bearing two distant, 

 slightly developed denticles. Greater diameter, 8| mm. ; lesser, 8 mm. ; height, 

 3 mm. 



1'riodoysis Harfordiana, W. G. BINNEY, not of J. G. COOPER, Terr. Moll., V. 309, 



figure only, not description : PL VIII. Fig. R, lingual dentition. 

 Mesodon devius, var., W. G. BLNN., Man. Anier. Land Shells, 118, Fig. 88. 



Salmon Eiver, Idaho (H. Hemphill). 



Genitalia unobserved. 



Lingual dentition (under erroneous name of Triodopsis Harfordiana'). See 

 Terr. Moll., V. 1. c. 



This is the shell formerly mistaken by me for Polygyra Harfordiana. It is 

 a small, very much depressed, shining shell, with open umbilicus and slightly 

 developed teeth. Its surface is scarred as if it had been hirsute. Though 

 much more depressed, it has the general appearance of a tiny T. tridentata. 



Triodopsis Hemphilli. 



Plate I. Fig. 17. 



Shell imperforate, globosely depressed, coarse, slightly wrinkled, russet- 

 colored, sparsely hirsute ; whorls five and a half, convex, the last globose, 

 slightly descending ; aperture very oblique, lunate, with a short, narrow, 

 slightly carving parietal tooth ; peristome white, broad, thickened, revolute, 

 usually quite concealing the umbilicus, bearing on its basal margin an elon- 

 gated, lamellar toothlike process. Greater diameter, 17 mm. ; lesser, 14 mm. ; 

 height, 7 mm. 



Kingston, Northern Idaho (J. Rand Sanburn). 



The surface is scarred as if hirsute when quite fresh. 



The shell, by its coarser texture, closed umbilicus, and lamellar peristome 

 denticle, is more nearly allied to the typical Mesodon devius than to Mullani, 

 Harfordiana, or Sanburni. Though common at the locality given above, it is 

 not variable, nor have" I received it from other points. 



Lingual membrane of the same character as in T. Sanburni. 



Genitalia as in the last-named species. 



Mesodon ptychophorus, A. D. BROWN. 



Plate I. Figs. 3, 16. 



Shell with umbilicus almost concealed, globose, with coarse, distant striae of 

 growth, thick, of a dull russet-color ; spire elevated, apex acute ; whorls five, con- 

 vex, the last swollen below, rapidly descending ; aperture oblique, subcircular, 

 parietal wall with light callus ; peristome white, thick, narrow, reflected, with 

 a thickening scarcely approaching a tooth-like process on its basal margin, its 



