The Echinoid Directory

• Test low subconical in profile.
• Apical disc small, hemicyclic with ocular plate insert. Periproct oval with small suranal plate distinct amongst periproctal plates; periproct opening offset towards ocular plate I.
• Ambulacra straight; plating polygeminate (5 elements to a plate), compounded in stomonpeustid style (middle element largest, with occluded elements both above and below). Pore-pairs undifferentiated; in alternating arcs of three and two pore-pairs. Slightly widened and more crowded adorally.
• A single primary tubercle to each triad compound plate alternating with a much smaller secondary tubercle close to pore zone on every diad. Granules forming zig-zag line down perradius.
• Interambulacral plates wider than tall; with a single primary tubercle, positioned centrally and scattered secondaries and granules interradially at the ambitus. Flanking secondary tubercles on adradial and interradial sides at the ambitus and below.
• A well developed naked interradial zone present aborally, expanding towards the apex.
• Tubercles imperforate and strongly crenulate.
• Peristome small, circular, with small, shallow buccal notches with thickened lip; no tag.
• Spines about half test diameter; simple, tapering to a point distally; with thin, smooth cortex.
• Lantern stirodont.

Eocene-Recent, Europe, Pacific.

Glyptocidaris crenularis Agassiz, 1864, p. 356, by original designation.

• G. crenularis Agassiz, 1863; Pliocene-Recent, Pacific.
• G. heteroporus (Lambert, 1898); Eocene, France.
• G. arctina (Nisiyama, 1966); ?Oligocene, Japan
• Possibly 'Echinometra' thomsoni d'Archaic & Haime, 1853; Eocene, Sind, Pakistan (poorly preserved test)

Stomopneustoida, Glyptocidaridae

Although previously placed in the Phymosomatidae, the ambulacral plate compounding style and the compact hemicyclic apical disc with smooth periproctal outline immediately distinguish this from all other members of that family. Its ambulacral plate compounding is similar in style to that of  Stomopneustidae, but those all have non-crenulate tubercles.  Jensen (1982) erected the family Glyptocidaridae to accommodate this genus.

Agassiz, A. 1863. Synopsis of the echinoids collected by Dr. W. Stimpson on the North Pacific Exploring Expedition under the Commandment of Captains Ringgold and Rodgers. Proceedings of the Academy of Natural Sciences of Philadelphia, 15, 352-361.

Clark, H. L. 1912. Hawaiian and other Pacific Echini. The Pedinidae, Phymosomatidae, Stomopneustidae, Echinidae, Temnopleuridae, Strongylocentrotidae and Echinometridae. Memoirs of the Museum of Comparative Zoology 34 (4), 180 pp., 32 pls.

Mortensen, T. 1935. A monograph of the Echinoidea II. Bothriocidaroida, Melonechinoida, Lepidocentroida and Stirodonta. C. A. Reitzel, Copenhagen.