The Echinoid Directory

Mepygurus Pomel, 1883, p. 65

Diagnostic Features
  • Test large, with flattened base and low domed upper surface, with greatest height at apical system. Anterior margin often blunt, posterior margin often pointed, greatest width central or posterior to centre. Adoral surface flat with interambulacra slightly raised and ambulacra depressed.
  • Apical system central or slightly anterior, tetrabasal, genital plate 2 is large, extending posteriorly, separating posterior genital plates, but not the posterior ocular plates which remain in contact.
  • Petals equal, broad and bowed, tapering distally; long, extending almost to margin; interporiferous zones very wide, poriferous zones wide with outer series of pores elongated into broad slits. Inner pores slightly elongated transversely, pores conjugate.
  • Periproct at posterior of oral surface, longitudinal, tear drop shaped with apex pointing adorally.
  • Peristome slightly anterior, pentagonal, width slightly greater than height; peristome sunken.
  • Bourrelets weakly convex, largely confined to vertical walled entrance of peristome.
  • Phyllodes long, with many pore pairs arranged in two series in each half- ambulacrum.
  • Tubercles on adoral surface a little larger than those on adapical surface; no naked zone in posterior interambulacrum.
Distribution
Bajocian to Oxfordian, Middle to Late Jurassic of Europe, Madagascar and Somalia.
Name gender masculine
Type
Pygurus fungiformis L. Agassiz, 1840, p. 5 [=Pygurus michelini Cotteau, 1849, p. 70; =Pygurus depressus L. Agassiz in Agassiz & Desor, 1847, p. 162]; by subsequent designation of Lambert & Thiery 1921, p. 356.
Species Included
  • M. depressus (A. Agassiz, in Agassiz & Desor, 1847); Bathonian-Callovian Middle Jurassic of France, Switzerland, England, Madagascar and Somalia.
  • M. michelini (Cotteau, 1849); Oxfordian, western Europe.
Classification and/or Status

Irregularia; Neognathostomata.

Subjective junior synonym of Astrolampas Pomel, 1883.

Remarks

Kier (1962) describes Mepygurus as a subgenus of Pygurus for such species that have a low, broad test, with a central or slightly anterior apical system, slightly depressed and not broadened phyllodes, with three or four series of pore pairs in each half ambulacrum, and with the first pore pair in a phyllode near the edge of the peristome. Pygurus differs from Mepygurus by having a somewhat inflated test, an anterior apical system, broad, depressed phyllodes, with from one to three series in each half ambulacrum, with the first pore pairs in a phyllode widely separated from the edge of the peristome.

P. M. Kier. 1962. Revision of the cassiduloid echinoids. Smithsonian Miscellaneous Collections, 144 (3) 262 pp.

Barras, C. G. 2006. British Jurassic irregular echinoids. Monograph of the Palaeontographical Society no. 625 (part of volume 159 for 2005), 1-168, pls 1-14.