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Hinge Teeth

A heterodon Hinge Close Small Key Text 3
Alasmidonta heterodondwarf wedgemussel

unique with 2 lateral teeth in the right valve, 1 in the left

E complanata Hinge Small Key Text
Elliptio complanataeastern elliptio

sharp, prominent laterals and large pseudocardinals

The hinge "teeth" are small structures of irregular shape and size that hold the two halves of the shell together.
A undulata Hinge Micro Key Text
Alasmidonta undulatatriangle floater

laterals may be vestigial, with heavy, triangular pseudocardinals

M margaritifera Hinge Key Text
Margaritifera margaritiferaeastern pearlshell

large, conspicuous, triangular pseudocardinals; laterals absent

The principal teeth are the pseudocardinals and the laterals; a few species have a third type, the interdental, that lies between the two.
L radiata Hinge Micro Key Text
Lampsilis radiataeastern lampmussel

laterals may be weak but clearly defined; interdentals present

S undulatus Hinge Key Text
Strophitus undulatuscreeper

some species have all teeth poorly defined or absent

Each type of tooth may be absent or vestigial, and their presence, absence and combination can be definitive for species identification.