Petalobrissus waltheri (Gauthier, 1900)

Mohamed Abdelhamid, Marouf Abdel-Aty & Moustafa Azab, Mahmoud, 2012, Turonian-Santonian echinoids from Egypt, Geodiversitas 34 (3), pp. 575-615 : 600

Petalobrissus waltheri (Gauthier, 1900) ( Fig. 11L, M)

Echinobrissus waltheri Gauthier in Fourtau, 1900: 21, pl. 1, figs 8-10.

Petalobrissus waltheri – Abdelhamid 1997: 148, fig. 6 (3, 4). — Kora et al. 2002: pl. 4, fig. 11.

MATERIAL EXAMINED. — 40 specimens from the Coniacian-Santonian of Abu Roash (Ostrea and Plicatula unit), ASUARE96-135, Abu Roash echinoid horizons 2-5 ( REH 2-5), 16 from the Coniacian-Santonian in Wadi Dakhl (Matulla Formation), ASUDLE22-37, Wadi Dakhl echinoid horizon 2 ( DEH 2), and 28 from the same stage of Wadi Abu Qaada, ASUAQE116-143, Wadi Abu Qaada echinoid horizon 5 ( QEH 5).

MEASUREMENTS. — See Table 11.

DESCRIPTION Test oval. Maximum width lies at end of the posterior paired petals. Anterior margin narrow. Posterior margin sub-round to straight. Adoral surface flattened, depressed around peristome. Apical disc tetrabasal. Ambulacral areas petaloid. Petals I, III, and V are relatively longer than petals II and IV. Pore pair conjugate, unequal, the outer slit-shaped, the inner round. All ambulacral plates beyond the petals are single-pored. Bourrelets occupy the vertical wall of peristome and part of interambulacra adjacent to peristome. Phyllodes moderately developed.

Order SPATANGOIDA Claus, 1876