Family Yoldiidae Key

Phylum Mollusca
Class Bivalvia
Subclass Protobranchia
Order Nuculida (Paleotaxodonta)

Taken primarily from Kozloff, 1987, 1996 p. 268 (Copyright 1987, 1996, University of Washington Press. Used in this web page by permission of University of Washington Press)

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Lower taxonomic level Main Page Alphabetic Index Systematic Index Glossary

1a Shell swollen, posterior end broadly truncate Yoldia (Megayoldia) thraciaeformis

1b Shell rather flat, not swollen; posterior end not truncate 2

2a Concentric sculpture not coinciding with growth lines (there are slight concentric ridges that cross the growth lines) (Y. scissurata in Kozloff key) Yoldia seminuda

2b Without any concentric sculpture other than growth lines 3

3a Umbones slightly posterior to the middle; length twice the height Yoldia (Yoldia) amygdalea

3b Umbones at the middle; length slightly less than twice the height Yoldia (Yoldia) myalis

Taxonomic Levels Represented in This Key:

Page created by Dave Cowles, 2006
Edited by:

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Lower taxonomic level	Main Page	Alphabetic Index	Systematic Index	Glossary

1a	Shell swollen, posterior end broadly truncate	Yoldia (Megayoldia) thraciaeformis
1b	Shell rather flat, not swollen; posterior end not truncate	2
2a	Concentric sculpture not coinciding with growth lines (there are slight concentric ridges that cross the growth lines) (Y. scissurata in Kozloff key)	Yoldia seminuda
2b	Without any concentric sculpture other than growth lines	3
3a	Umbones slightly posterior to the middle; length twice the height	Yoldia (Yoldia) amygdalea
3b	Umbones at the middle; length slightly less than twice the height	Yoldia (Yoldia) myalis