Taken primarily from Kozloff, 1987, 1996 (Copyright 1987, 1996, University of Washington Press. Used in this web page by permission of University of Washington Press)
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| Lower taxonomic level | Main Page | Alphabetic Index | Systematic Index | Glossary |
| 1a | Outer lip of the aperture with a sharp tooth slightly below the middle (smaller specimens may, however, lack the tooth); with interrupted dark spiral bands (uncommon north of California) (picture) | Acanthina spirata
(Blainville, 1832) |
| 1b | Outer lip of aperture without a sharp tooth (picture ); without interruped dark spiral bands | 2 |
| 2a | Axial sculpture consisting of frilly lamellae (picture); spiral sculpture (which may be obscured by the lamellae) consisting of 1 or 2 prominent ridges on each whorl (height up to 10 cm) (picture ) | Nucella lamellosa
(Gmelin, 1791) |
| 2b | Axial sculpture, if noticeable, cosisting either of broad ribs or low wrinkles; spiral sculpture consisting either of 1 or 2 prominent ridges on each whorl, or of numerous closely spaced ridges | 3 |
| 3a | Spiral sculpture consisting of 1 or 2 prominent ridges on each whorl (but the lower part of the body whorl usually has several smaller ridges), the whorls flattened between the ridges and the sutures, thus appearing angled; height up to about 10 cm. [Specimens that fit under this choice are typical of situations where currents are strong or where there is considerable wave action--in which case the axial lamellae may not be present]. (picture) | Nucella lamellosa
(Gmelin, 1791) |
| 3b | Spiral sculpture consisting of closely spaced ridges (in some specimens of Nucella emarginata, however, the ridges are obscure); height rarely exceeding 3 cm | 4 |
| 4a | Spiral ridges generally of 2 sizes, the smaller ones alternating with the larger ones; whorls not separated from one another by a deep groove (picture) | 5 |
| 4b | Spiral ridges generally of nearly equal size; whorls usually separated from one another by a deep groove | Nucella canaliculata
(Duclos, 1832) |
| 5a | Shell relatively thin; width of the aperture about half the diameter of the shell (not likely to be found south of the northern part of Vancouver Island) | Nucella lima
(Gmelin, 1791) |
| 5b | Shell relatively thick, the thickness being especially noticeable on the outer lip of the aperture; width of aperture (the actual opening) less than half the diameter of the shell (interior of aperture often purplish brown; common) (picture) | Nucella emarginata
(Deshayes, 1839) |
Acanthina spirata
Nucella canaliculata
Nucella lamellosa
Nucella emarginata
