Thomas Wright

 in T. WRIGHT (1857-1878) Monograph on the British Bossil Echinodermata of the Oolitic Formations

Vol.I - The Echinoidea, foreign oolitic cidaridae, page 66.


D. Species from the Kimmeridge Clay.

RHABDOCIDARIS ORBIGNYANA. Desor, Synopsis des Echinides Fossiles, p.40, t. 1, fig. 3.

Test large, spheroidal ; ambulacra broad, flat, with four rows of granules ; poriferous zones as wide as the area ; pores small, orund, placed far apart by thick septa ; interambulacra with seven or eight plates in a column ; areola circular, superficial ; boss prominent, summit broad and deeply crenulated ; tubercles large and widely perforated ; scrobicular circles complete ; granules small, well spaced out, and raised on a base ; miliary zone moderately wide, and filled with small granules, which gradually diminish in size between the scrobicular circle and the centro-sutural line, which is well defined. Spines long, tricarinate or prismatic, from three to four inches in length ; sometimes they are compressed and flattened near their distal extremity ; the head is small, the rim of the acetabulum is deeply crenulated, the ring is narrow, the neck short and smooth ; at the base, and along the edges of the carinae, there are rows of stout, short, forward-directed, thorn-like prickles ; the intermediate surface of the stem is covered with longitudinal lines of small, irregular-sized granules.

Formation. - Kimmeridge Clay, Rochelle, Villersville, Cap la Hève, Havre.

Collections. - MM. Michelin, Cotteau, Thurmann.

                     British Museum, Jermyn Street Museum, my Cabinet.