The Echinoid Directory

Key to genera of Pourtalesiidae

1a. Periproct aboral and with subanal rostrum with ring-like subanal fasciole.
Go to 2

1b. No subanal rostrum. Periproct marginal or inframarginal.

Go to 5

2a. Anterior of test (towards top) extended out making the test vase-like.

Echinosigra

2b. Anterior of test (towards left) not extended.

Go to 3

3a. Anterior (to right) broadened and bilobed so that test outline is triangular.

Ceratophysa

3b. Test cylindrical at anterior (to left).

Go to 4

4a. Plating in posterior ambulacra continuous.

Helgocystis

4b. Posterior ambulacral plating disjunct; separated by plates of interambulacra 1 and 4 meeting along the midline.

Pourtalesia