The Echinoid Directory

Key to the genera of unnamed family 1


1a. Apical disc with two gonopores only, the right anterior and right posterior gonopores being absent Plesiopatangus	1b. Apical disc with four gonopores Go to 2

2a. Distinct oral groove leading to the peristome on oral surface Go to 3	2b. No oral groove leading to the peristome on oral surface. Go to 4

3a. Peristome closer to centre than anterior; no subanal heel. Migliorinia	3b. Peristome anterior; stronlgy developed subanal projection. Cionobrissus

4a. Primary tubercles present only in posterior column of plates in paired interambulacra. Gillechinus	4b. Tuberculation not obviously different on anterior and posterior columns of lateral paired interambulacra. Go to 5

5a. Anterior petals short. Peristome not subcentral Brissopatagus	5b. Anterior petals apparently long; peristome subcentral Hikelaster