Definition of Pentamerus
: a genus (the type of the family Pentameridae) comprising Paleozoic brachiopods of the order Protremata abundant in the Silurian and having the shell rostrate and oval or somewhat pentagonal with its cavity divided by two internal vertical ridges and a spondylium in each valve
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Origin and Etymology of pentamerus
New Latin, from penta- (from Greek) + -merus -merous
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