The Echinoid Directory
Key to major clades of Laganiformes
For alternative key see Mooi, R. 1989. Living and fossil genera of the Clypeasteroida (Echinoidea: Echinodermata): an illustrated key and annotated checklist. Smithsonian Contributions to Zoology 488, 1-51. |
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1a.Test small and ovate, without internal buttressing (internal view of oral surface pictured above). |
1b.Test always with internal buttressing (internal view of apical surface pictured above). |
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2a.Basicoronal interambulacral plate internals so that first circlet surrounding peristome externally is composed of 20 plates (see above). |
2b.Basicoronal interambulacral plates visible externally so that first circlet surrounding peristome composed of 15 plates (see above). |
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3a.Internal buttressing comprises simple unbranched radial partitions. Basicoronal ambulacral plates not projecting. |
3b.Internal buttressing comprises more complex branched radial partitions and circumferential walls. Basicoronal ambulacral plates pentagonal or pentastellate. |