Key:  Subfamily Lacuninae of Family Littorinidae (Formerly Family Lacunidae)

Phylum Mollusca
  Class Gastropoda
    Subclass Prosobranchia
      Order Mesogastropoda
        Suborder Taenioglossa
          Family Littorinidae

Taken primarily from  Kozloff, 1987, 1996 p. 208 (Copyright 1987, 1996, University of Washington Press.  Used in this web page by permission of University of Washington Press)

Note:  This key is not reliable for very young specimens (shell height under 3 mm)
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1a  Height of aperture nearly or fully two-thirds the height of the shell 2
1b Height of aperture about half the height of the shell (in some specimens of Lacuna variegata the height of the aperture is slightly more than half the height of the shell, but definitely not two-thirds the height) 3
2a Shell glossy brown, often with lighter mottling, without wrinkles, but sometimes with faint spiral lines; height up to about 6 mm (not likely to be found north of Oregon) Lacuna (Lacuna) marmorata
2b Shell dull grown, usually without mottling, but with microscopic wrinkles (in general, the wrinkles are oriented in much the same way as spiral lines or ridges, but they are more irregular) Lacuna (Lacuna) porrecta
3a Shell mostly light tan, with chevron markings of brown under a thin, dull periostracum; without distinct spiral lines; larger whorls sometimes with a slight, flattened shoulder; height up to about 7 mm; common on Zostera (eelgrass) in bays (not likely to be found south of Washington) Lacuna (Epheria) variegata
3b Shell tan or brown, usually with a broad, whitish spiral band under a glossy periostracum; with fine spiral lines; whorls evenly rounded; height up to 1.3 cm; on algae on rocky shores (not likely to be found south of Washington) Lacuna (Epheria) vincta

Taxonomic Levels Represented in This Key:

Lacuna variegata
Lacuna vincta

Page created by Dave Cowles, 2008
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