The Echinoid Directory

Polycyphus L. Agassiz, in Agassiz & Desor, 1846, p. 361

Diagnostic Features
  • Test domed, flattened below.
  • Apical disc small, subcircular; dicyclic with genital plates a little wider than tall. G2 enlarged compared to others. Oculars small. periproct large subpolygonal. Ring of tubercles on genital plates.
  • Ambulacra trigeminate with pore-pairs in strong arcs forming adradial band throughout. Plate compounding arbaciid, with upper and lower elements narrow wedge-shaped elements that end before reaching the perradius. Adapically all elements reach perradius. Short phyllodes developed adorally.
  • Ambulacral plates generally with single tubercle close to perradial band. Second, slightly smaller tubercle present perradially on ambital and adoral plates. Dense granulation elsewhere.
  • Interambulacral plates wider than tall. A single primary tubercle centrally placed, with smaller secondary flanking tubercles on adradial and interradial sides on adapical plates; becoming as row of subequal tubercles, up to 4 abreast at ambitus and 2 adorally; marked increase in size of tubercles.
  • Ambulacral and interambulacral tubercles of similar size.
  • Narrow aboral naked interradial zone.
  • Primary tubercles imperforate and non-crenulate.
  • Peristome large, weakly sunken; buccal notches moderately deep and sharp.
  • Spines and lantern unknown; no primordial interambulacral plate.
Middle-Upper Jurassic, Europe, North Africa, Arabian Peninsula.
Name gender masculine
Polycyphus nodulosus Agassiz & Desor, 1846, p. 361 (non Munster), by monotypy [= Polycyphus normannus Desor, 1858, p. 117]
Species Included
  • P. normannus Desor, 1848; Bathonian, western Europe.
  • P. arabicus Kier, 1972; Bathonian, Saudi Arabia.
  • P. paucituberculatus Kier, 1972; Callovian, Saudi Arabia.
Classification and/or Status
Euechinoidea, Echinacea, Stomechinidae.

Distinguished from Stomechinus and Psephechinus by having interambulacral tubercles above the ambitus arranged into well-defined vertical columns.

The name Polycyphus was first proposed by Agassiz & Desor (1846) for a specimen originally identified as Polycyphus nodulosus (Munster) but later renamed Polycyphus normannus by Desor (1858) who correctly recognized its distinction from Munster\'s species.

Agassiz, L. & Desor, P. J. E. 1846-1847. Catalogue raisonné des familles, des genres, et des espèces de la classe des échinodermes. Annales des Sciences Naturelles, Troisième Série, Zoologie : 6 (1846): 305-374, pls. 15-16; 7 (1847): 129-168; 8 (1847): 5-35, 355-380.