ECHINODERMATA. 53 



E. Species from the Kimmeridge Clay. 



[Spines of which the test is unknown.] 

 Cidaris spinosa, Agassiz. PL XII, fig. 4. 



Cidaeis spinosa. Agassiz, Echinodermes Fossiles de la Suisse, part ii, p. 71, pi. 21, fig. a. 



— — Desor, Synopsis des Echinides Fossiles, p. 25, t. 3, fig. 2. 



— — Morris, Catalogue of British Fossils, 2d edit., p. 75. 



The principal character of this species consists in the prominent thorny processes 

 which project from the surface of its stem, which is round and slender, and is likewise 

 finely marked with longitudinal lines ; the neck is short. It is exceedingly difficult to deter- 

 mine from a single spine, without comparing it with the type, whether that which is figured 

 is identical with the Cidaris spinosa, Agass. It certainly comes nearest to that form with 

 which it is provisionally placed. It was collected from the Kimmeridge Clay of Aylesbury. 



Cidaris Boloniensis, Wright. PL XII, fig. 5. 



Spine long, nearly two inches in length ; acetabulum deeply crenulated ; ring promi- 

 nent, acutely carinated ; neck long, slender, smooth ; stem flattened, covered with finely 

 granulated longitudinal ridges, which have prominent, thorn-like, forward-directed pro- 

 cesses, developed at irregular intervals on the stem, which is flat and oar-like at its distal 

 extremity. On this blade-like termination there are sometimes prominent, longitudinal 

 carinas, formed by the excessive development of the terminal granulated lines. 



Affinities and differences. — This spine resembles that of Cidaris Orhignyana in its 

 general characters; but it has a longer neck, a more prominent and acutely carinated ring, 

 and the stem is likewise furnished with stouter thorn-like processes; in the flattened 

 condition of the distal extremity it resembles that species. It is altogether a stronger and 

 larger spine than that referred to Cidaris spinosa, and its long, smooth neck serves to 

 distinguish it from that species. 



Locality and Stratigraphical position. — Collected by the late Hugh Strickland, Esq., 

 from the Kimmeridge Clay, Dorset. The same species* has been found by M. Bouchard 

 Chantereaux, who kindly sent me a series of spines, from the Kimmeridge Clay near 

 Boulogne-sur-Mer, where it is very rare. 



* 'Notes on Foreign Jurassic Species,' page 63. 



