The Echinoid Directory

• Test large, circular in outline, domed, adoral surface flat.
• Apical system monobasal, with small ocular plates; central.
• Petals long, extending almost to margin, moderately wide, with interporiferous zones four times the width of poriferous zones. Pores slightly conjugate, outer pore of pore-pair slightly elongated transversely, inner pore round; poriferous zones of slightly unequal length in the same petal.
• Periproct situated on the flat oral surface, transverse.
• Peristome, subcentral, transverse, subpentagonal. Ambulacral zones distinctly sunken approaching the peristome.
• Bourrelets: phyllodes sunken creating 'pseudobourrelets' which incorporate post-basicoronal plates, forming rounded mounds close to peristome.
• Phyllodes well developed, slight broadening near peristome, single pored, with many pore-pairs arranged in three series in each half-ambulacrum.
• Buccal pores present.

Middle to Late Miocene (Langhian-Helvetian) of Europe and North Africa.

Galerites semiglobus Lamarck, 1816, p. 22; by original designation.

• H. hemisphaericus Gregory, 1891; Helvetian, Malta.
• H. semiglobus (Lamarck, 1816); Tortonian-Helvetian, Europe.

Irregularia; Cassiduloida; Echinolampadidae.

Subjective junior synonym of Hypsoclypus Pomel, 1869.

Heteroclypeus is very similar to Hypsoclypus to the extent that they are treated here as subjective synonyms. The type species of Heteroclypeus differs slightly from the type species of Hypsoclypus in that the ambulacra leading into the peristome are more distinctly sunken, resulting in very prominent pseudobourrelets. This character is variable in its development among species of Hypsoclypus and is therefore not worthy of generic distinction.

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