66 FOREIGN OOLITIC CIDARIDiE. 



surface covered with short, thorn-Hke, 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, Wiirttemberg. Formation e, Querist. 



Collections. — Museums of Vienna, Tiibingen, Stuttgart. 

 British Museum, my Cabinet. 



D. Species from the Kimmeridge Clay. 

 Rabdocidaris Orbigntana. 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 carinse, 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. 



