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1a. Internal fasciole (yellow) present, crossing paired ambulacra between the apical disc and the petal end. |
1b. No fasciole bisecting the petals. |
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2b. No peripetalous fasciole bounding the ends of the petals. |
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4b. Petals only weakly developed and not forming lateral arc.
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5a.Anterior column of pores in anterior petal microscopic.
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5b. Anterior column of pore-pairs developed in distal part of petals. |
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6a. Sternal plates tuberculate only in posterior region. Anterior petals narrow and subparallel. |
6b. Sternal plates fully tuberculate. Petals oviously tapered distally. |