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

#1

Ovate-trigonal, strongly inequivalve LV fitting deeply into RV. Juveniles subquadrate with spines on dorsal margin

Elongate, subelliptical, posterior becoming truncate in some, some rather irregular

#2

Beaks towards the anterior, adult shells rather wedge shaped, obliquely truncated posteriorly with a faint posterior angulation, pallial sinus short reaching about halfway to point below chondrophore

Sphenia binghami

Beaks close to midline

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#3

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Shells less than 10mm, juvenile

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Shells more than 10mm, closer to adult

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#4

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Adult shells subelliptical, beaks close to midline, posterior narrowly rounded, pallial sinus narrowly rounded, extending to point below chondrophore

Mya arenaria

Adult shells truncate posteriorly or rather irregular but beaks well in front of midline, pallial sinus broad, truncated, extending to point below chondrophore

Mya truncata

#5

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Subovate, beak towards anterior, posterior dorsal slope steep

Mya arenaria

Broadly rounded anterior with beak at midline, posterior dorsal slope is shallow

Mya truncata