A. Whitneyi Rémond.
Disk circular, or sub-pentagonal, slightly notched at the extremity of the ambulacra.
Apex central and elevated; edge depressed.
Ambulacral star symmetrical, prominent near the apex; petals equal, reaching to the margin of the disk.
Interambulacral spaces much depressed near the edge.
Lower surface slightly and gradually concave; furrows well marked and straight.
Mouth central, circular; anal aperture small, sub-marginal.
Papillary tubercles somewhat remote, smaller above than beneath, situated in wide and shallow cells; miliary tubercles very numerous and crowded, both on the superior and inferior surfaces.
| Greatest diameter | 1.8 | inches |
| Smallest diameter | 1.65 | ” |
| Height | 0.3 | ” |
Locality: Kirker’s Pass formations. Found in lower pliocene beds.