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Girardema Vadet, 1993, p. 88

Diagnostic Features	"Close to Polydiadema and Diplopodia but distinguished by the structure of the adapical pore zone.  In the same assemblage certain individuals  have all the adapical zygopores in a row, some in two rows, some in a mixture" Vadet (1993. p. 88)
Distribution	Middle Jurassic (Aalenian-Bajocian), France and England.
Name gender	neuter
Type	Diadema depressum (Agassiz, in Agassiz & Desor, 1846, p.349), by original designation
Species Included	One other species was included: Diplopodia bipunctata Desor, 1857.
Classification and/or Status	Carinacea, Phymosomatoida, Emiratiidae Subjective junior synonym of Polydiadema
Remarks	The heterogeneity of pore-pair arrangement suggested by Vadet (1993) is not evident in the large population of 'Diadema depressum' from the Pea Grit of the Cotswolds, England.  In all respects this species falls clearly into synonymy with Trochotiara and Polydiadema, although it more rarely has an extra element in ambital ambulacral plates.  Agassiz's type material came from the Inferior Oolite of Ranville, Nomandie, France. Vadet, A. 1993. Les oursins du Bathonien et du Bajocien de Normandie. Memoires de la Societe academique du Boulonnais 6(3-4), 1-104.