The Echinoid Directory

Contributed by Jenna Sullivan, April 2007

Clypeus muelleri Wright, 1859, p. 371

Diagnostic Features Clypeus species in which the apical disc contains one or more complemental plates lying to posterior of madreporite. Within petals, outer pore highly elongate (pore length over 2.5% of test length). Petals end before ambitus (Barras, 2006, p. 100).
Distribution Upper Bajocian, parkinsoni Zone of Gloucestershire; Bajocian of Gloucestershire and Oxfordshire; Middle Bathonian, progracilis Zone of Oxfordshire; Middle Bathonian, subcontractus Zone of Oxfordshire and Gloucestershire; Upper Bathonian, hodsoni Zone, of Gloucestershire; Bathonian of Gloucestershire, Oxfordshire, and Cambridgeshire; Bajocian of Soleurois, Switzerland; Bathonian of Neuchatel, Switzerland; Lower Bathonian of Pas-de-Calais, France.
Type Syntypes: Natural History Museum, London E1662 and E4504.
Classification and/or Status Species of Clypeus.
Remarks Differs from C. plotii in that the petals of C. muelleri end before the ambitus while those of C. plotii stretch to the ambitus. Unlike C. plotii, well-preserved specimins of C. muelleri show the presence of one or more small complemental plates to the immediate posterior of the madreporite. Within the petals of C. muelleri, the outer pore of each pore-paire is elongate to a much greater degree than in C. rostratus. In detail, the outer pore of each pore-pair within the petals is over four times the width of the inner pore in C. muelleri, but around two to three times the width of the inner pore in C. rostratus. (Barras, 2006, p. 102).

Barras, C. G. 2006. British Jurassic Irregular Echinoides. Monograph of the Palaeontographical Society, London.

Wright, T. 1859. Monograph on the British Fossil Echinodermata of the Oolite Formations. I, the Echinoidea, Monographs of the Palaeontographical Society, London. p. 303-390, pls 23-36.