| 1. Size in millimeters |
| 137Under 5 865 to 10 32210 to 25 58Over 25 |
| 2. Shell proportions |
| 252Taller than wide | 304Wider than tall |
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| 3. Spire angle in degrees |
| 172Under 30 | 7730-60 | 5860-90 | 13790-120 | 127120-150 | 21150-180 |
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| 4. Aperture shape |
| 3Bean | 71Crescent | 97Half-moon | 176Oval or teardrop | 147Round | 88Taller than wide, top angle acute | 35Teeth constrict aperture |
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| 5. Whorls, number of , range |
| 73Under 4 | 3174-6 | 1826-10 | 31Over 10 |
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| 6. Outer lip flared |
| 246No | 71Slightly | 252Strongly |
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| 7. Sculpture, axial, on last whorl |
| 13Absent | 345Growth lines only | 231Ribs or grooves |
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| 8. Sculpture, spiral, on last whorl |
| 388Absent | 146Cords |
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| 9. Aperture, top, junction with previous whorl |
| 89Acute | 59None, detached | 286Oblique | 69Radial | 77Tangential or almost so |
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| 10. Teeth / ridges / lamellae in aperture |
| 488Absent | 60Present |
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