The Echinoid Directory

Key to the genera of Brissidae: 1

1a. Subanal fasciole shield-shaped; approximately as wide as tall.
Go to 6

1b. Subanal fasciole bilobed, with two distinct centres of enlarged spines and tubercles, one on either side of the midline.

Go to 2

2a. Anterior petals almost at 180 degrees to one another. Lateral interambulacra amphiplacous. Frontal groove absent.

Go to 3

2b. Anterior petals cruciform. Lateral interambulacra meridoplacous. Frontal groove present at ambitus.

Go to 4
3a. Petals well developed and sunken. Four gonopores.

3b. Petals weakly developed and almost flush. Three gonopores.


4a. Ambulacrum III hardly indented at the ambitus. Petals relatively long.


4b. Ambulacrum III forming a deep notch at the ambitus. Petals relatively short.

Go to 5

5a.Primary tubercles developed in posterior column of lateral interambulacra only inside peripetalous fasciole. Peripetalous fasciole not indented behind anterior petals.

5b. Primary tubercles absent; tuberculation generally rather coarser and more heterogeneous inside peripetalous fasicole. Peripetalous fasciole indented interradially.