The Echinoid Directory

1a. Internal fasciole (yellow) present, crossing paired ambulacra between the apical disc and the petal end.

1b. No fasciole bisecting the petals.

2a. Peripetalous fasciole present bounding the ends of the petals in addition to internal fasciole.

2b. No peripetalous fasciole bounding the ends of the petals.

3a. Inner fasciole closer to outer ends of petals than apical disc, with well-developed pore pairs present both inside and outside the fasciole.

3b. Pore-pairs rudimentary inside inner fasciole, so that petal pore-pairs are restricted to zone outside the inner fasciole.

4a. Petals well-developed, forming near continuous arc laterally.

4b. Petals only weakly developed and not forming lateral arc.

Pseudolovenia

5a.Anterior column of pores in anterior petal microscopic.

Hemipatagus

5b. Anterior column of pore-pairs developed in distal part of petals.

6a. Sternal plates tuberculate only in posterior region. Anterior petals narrow and subparallel.

6b. Sternal plates fully tuberculate. Petals oviously tapered distally.