Limoidea | ID Keys | Marine Bivalve Shells of the British Isles

#1

Shells distinctly asymmetric

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Shells more or less symmetrical

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#2

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Anterior ear lacking, anterior slope long and straight

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Anterior and posterior ears developed

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#3

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Radially striated with up to 100 riblets

Acesta excavata

With c.30 prominent ribs bearing small scales especially anteriorly

Lima marioni

#4

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With large anterior and posterior gapes

Limaria hians

Valves meeting all round

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#5

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Radial riblets prominent, median 20 strongest

Limaria loscombi

Small, not exceeding 5mm, shell glassy, with few radial striations (Biscay)

Limatula demiradiata

#6

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Hinge plate either side of ligament with denticles

Limea crassa

Hinge plate smooth

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#7

Median riblets distinctly larger, expressed internally as a groove

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Median riblets not disproportionately developed

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#8

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Sculpture of the median riblet only, small shells <2mm

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Sculpture of numerous radial riblets

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#9

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Ears slightly projecting

Ears indistinct

#10

Outline elliptical much narrower dorsally and ventrally

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Outline narrowly oblong

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#11

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Hinge line oblique, about 40 riblets, ears not well developed

Limatula celtica

Hinge line horizontal, about 50 riblets, ears prominent

Limatula subovata

#12

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Outline narrowly oblong, ears weak, 22-26 marginal crenulations

Limatula subauriculata

Outline oblong, ears distinct, 25-30 marginal crenulations

Limatula gwyni

#13

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Outline narrowly oblong, with about 38 fine radial riblets

Limatula thalassae

Outline oval with less than 33 riblets

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#14

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Anterior slope much straighter than posterior, 22-26 riblets

Limatula jeffreysi

Curvatures of anterior and posterior not noticeably discrepant, 27-33 riblets

Limatula margaretae