The Echinoid Directory

Key to the genera of Aeropsidae

1a. Ambulacra apetaloid or weakly subpetaloid aborally.
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1b. Ambulacra petaloid aborally and sunken; frontal groove present.

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2a. Adapical pores in amb III enlarged and clearly differentiated.

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2b. Adapical pores in amb III small and rudimentary or not differentiated from those in the paired ambulacra.

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3a. Wedge-shaped in profile; peristome anterior.

3b. Cylindrical in profile; peristome closer to centre than anterior.

4a. Strong subanal projection with periproct clearly aboral.

4b. Test only weakly projecting beneath periproct.

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5a.No sulcus on oral surface leading to peristome. Sternal plates asymmetric.

5b. Frontal sulcus leading to peristome. Sternal plates symmetric.
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6a. Peristome close to the anterior border; subglobular in profile.

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6b. Peristome well removed from the anterior border; subconical in profile.


7a. Apical disc with four gonopores.


7b. Apical disc with three gonopores.

8a. Shallow anterior sulcus; no subanal heel.
8b. Deep anterior sulcus; well developed subanal heel.