C6 FOREIGN OOLITIC CIDARIDtE. 



surface covered with short, thorn-like, forward-directed prickles, which in prismatic varieties 

 are disposed in lines ; base of the stem slightly enlarged ; the remainder of the stem is 

 narrower, and of a uniform width throughout. 



Formation. — White Jura (Argovien) ? Baireuth. 



White Jura, Coral Rag, Wurttemberg. Formation a, Quenst. 



Collections. — Museums of Vienna, Tubingen, Stuttgart. 

 British Museum, my Cabinet. 



D. Species from the Kimmeridge Clay. 

 Rabdocidaris 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, round, placed far apart by thick septa ; inter- 

 ambulacra with seven or eight plates in a column ; areola circular, superficial ; boss promi- 

 nent, summit broad and deeply crenulated ; tubercles large and widely perforated ; scrobi- 

 cular 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, tri- 

 carinate 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 carinas, 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 Heve, Havre. 



Collections. — MM. Michelin, Cotteau, Thurmann. 



British Museum, Jermyn Street Museum, my Cabinet. 



