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. 

 19: 48; 4. signwides (Mo.) {vitrinoides 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) (graninn Strebel, gnatemalensis C. and F.) 



EE. Umbilicus larger (lo-ii in diameter) ; suture more deeply 



impressed. 2.8; 100; 4^2. plagioptycha (Shuttleworth) 



DDD. More depressed species; umbilicus larger (less than 7 



times in diameter. 



F. Smallest species: 2.55; 84; 4. 



fiiscula (C. B. A.) (fischeri Pils.) 

 FF. Larger: 3.7; 76; 414. proximo Pilsbry 



FFF. Largest: 4.6; 83; 4^. canalis Pilsbry 



CC. Conical shell ; last whorl subangulate. 



G. Larger: 5; 80; 5. turbinella (Morelet) ?? 



GG. Smaller: 4.5; 78; 5 paleosa (Strebel) 



BE. 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. 

 L 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 kornii (Gabb) 



IL 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. 



