56 University of Michigan 
tendency to be arranged in diamond-shaped patterns; and with 
regularly spaced, much larger, papilla-like bosses, arranged in a 
definite pattern so as to form rows more oblique than the growth- 
lines and also rows less oblique. Large shell with concave apex. 
TO) cbske Al, sigmoides (Mo.) (wvitrinoides Trm.) 
AAA. Apical whorls with cuticular riblets, more oblique than, and 
crossing, the growth-lines. 
B. Oblique, cuticular riblets over entire shell. 
C. Whorls rounded. 
D. Most elevated forms; cuticular riblets tend to die out on 
body whorl. 2.5; 112; 5. rhoadsi Pilsbry 
DD. Not quite so elevated; about as high as wide. 
E. Umbilicus minute, rimate; suture less deeply impressed. 
3; 100; 4. 
caecoides (Tate) (granum Strebel, guatemalensis C. and F.) 
EE. Umbilicus larger (10-11 in diameter) ; suture more deeply 
impressed. 2.8; 100; 4%. plagioptycha (Shuttleworth) 
DDD. More depressed species; umbilicus larger (less than 7 
times in diameter. 
F. Smallest species: 2.55; 84; 4. 
fuscula (C. B. A.) (fischeri Pils.) 
HES ie ancens 77 Osn4uee proxima Pilsbry 
FFF. Largest: 4.6; 83; 434. canalis Pilsbry 
CC. Conical shell; last whorl subangulate. 
G, Ilavreeres 2 eos 8: _ turbinella (Morelet) ?? 
GG. Smaller: 4.5; 78; 5 paleosa (Strebel) 
BB. Oblique riblets represented on last whorls by oblique rows of 
crescentic projections; shell discoid. 
- (Thysanophora s. s.) conspurcatella (Morelet) 
AAAA. Apical whorls with wrinkles or riblets parallel to growth- 
lines. 
H. Apical whorls also with rather indistinct spiral striations, which 
tend to give the radial wrinkles a beaded appearance. 
I. Lower whorls with rather distant, long, hair-like processes, 
arranged so as to form a diamond-pattern with oblique rows 
crossing the growth-lines, both more and less obliquely. 
K. Smaller and more elevated: 2; 90; 6. intonsa Pilsbry 
KK. Larger and discoid: 4; 62; 4  kornit (Gabb) 
II. Without hair-like processes, as far as observed. 
L. Entire shell with fine, close-set and irregular, anastamosing, 
radial wrinkles or minute riblets; spiral striation less well 
marked. 
