The Echinoid Directory

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Key to the genera of Echinoneidae

1a.Ambulacra petaloid. Go to 2		1b.Ambulacra apetaloid; pore-pairs undifferentiated. Go to 3
2a.Apical disc anterior; periproct less than twice as long as wide. Paramblypygus		2b.Apical disc central; periproct more than twice as long as wide. Amblypygus
3a.Periproct inframarginal (test seen in posterior view); pyrinoid plating absent at ambitus and above. Numerous interambulacral plates separate the peristome and periproct. Duperieria		3b.Periproct oral (test seen in posterior view); pyrinoid plating present throughout. Just one interambulacral plate separates the peristome and periproct. Go to 4
4a.Periproct more or less bilaterally symmetrical. Go to 5		4b.Periproct distinctly oblique. Micropetalon
5a. All primary tubercles imperforate. Echinoneus		5b. All primary tubercles with distinct perforation. Koehleraster