Rhombifera

Classification
Phylum: Echinodermata
Class: Rhombifera (Zittel, 1879)
Cincinnatian Orders: Dichoporita, Glyptocystitida

Geologic Range
Early Ordovician – Late Devonian

Common Paleoecology
Rhombifera is an extinct class of stationary intermediate-level epifaunal suspension feeders

Characteristics of the Class

• Thecal pores arranged in rhombs
• Food grooves exothecal
• Stereom and stroma arranged in folds and strands at right angles to the sutures of the thecal plates

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Treatise on Invertebrate Paleontology, Part T, Vol. 1(1) (1967):

• Thecal pores developed as dichopores, arranged in rhombs in which each unit or dichopore is shared by 2 adjacent plates

Bather (1900):

• Emended from Zittel (1879): Cystidea in which radial symmetry affects the food-grooves, and, in the more advanced families, the thecal plates; probably also the nerves and ambulacral vessels, but not the gonads. The food grooves are exothecal, i.e. are stretched out from the theca on jointed skeletal processes (brachioles). These either are close to the mouth or are removed from it upon a series of ambulacral or subambulacral plates not derived immediately from thecal plates, or are separated from the oral centre by hypothecal passages passing beneath tegminal plates. The stereom and stroma become arranged in folds and strands at right angles to the sutures of the thecal plates; in higher forms, the stereom-folds are in part specialised as pectini-rhombs.

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