The Echinoid Directory
Key to genera of Laganinae
 |
 |
|
1a.Internal buttressing comprises radial elements with lateral branches. |
1b.Internal buttressing more complex. |
 |
 |
|
2a.Four gonopores; hydropores scattered over surface. |
2b.Five gonopores; hydropores in groove or pit. |
 |
 |
|
3a.Periproct situated midlength between peristome and posterior margin (first paired interambulacral plates short). |
3b.Periproct situated close to posterior margin (first paired interambulacral plates greatly elongate). |
 |
 |
|
4a.Petals about half the radius. |
4b.Petals extend most of the distance to the ambitus. |
 |
 |
|
5a.Periproct bounded by first and second post-basicoronal interambulacral plates. |
5b.Periproct opening posterior to first and second post-basicoronal interambulacral plates. |
 |
|
|
6a. Interambulacral zones only slightly narrower than ambulacral zones at ambitus. |
6b. Interambulacral zones very much narrower than ambulacral zones at ambitus. |