Key:  Family Capulidae (Formerly Trichotropidae)

Taken primarily from  Kozloff, 1987, 1996 p. 216 (Copyright 1987, 1996, University of Washington Press.  Used in this web page by permission of University of Washington Press)

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1a	Diameter about two-thirds of the height; height of aperture about half or slightly less than half the total height of the shell	2
1b	Diameter more than two thirds of the height; height of aperture about two-thirds the total height of the shell	3
2a	Height of aperture usually slightly less than half the height of the shell (common shallow subtidal species, and occasionally found intertidally)	Trichotropis cancellata
2b	Height of aperture about half, or slightly more than half, the height of the shell (rare subtidal species)	Trichotropis borealis
3a	With 2 pronounced spiral ridges on the body whorl, these not separated by smaller ridges; lowermost part of aperture rather sharply angled; height up to 5 cm (rare subtidal species; not likely to be found south of British Columbia	Trichotropis bicarinata
3b	With 2 pronounced ridges on the body whorl, these separated by several smaller ridges; lowermost part of aperture not sharply angled (the outline of the aperture is nearly circular); height to 2.5 cm (rare subtidal species)	Trichotropis insignis

  Trichotropis cancellata