NO. 3 CASSIDULOID ECHINOIDS — KIER 33 



Shape. — Large, flattened, circular, greatest height at center, an- 

 terior to apical system, adoral surface flat or depressed. 



Apical system. — Posterior to center, tetrabasal (text fig. 14 for 

 C. sinuatus), madreporite large, extending posteriorly to posterior 

 oculars, greatly separating posterior genital plates, other genital plates 

 small, triangular, pore in genital plate 3 more anterior than pore in 

 genital plate 2. Posterior oculars prolonged posteriorly, extending 

 to opening of periproct. 



Ambitlacra. — Petals broad, long, extending to margin, open. Petals 

 II, III, IV, longer than V, I. Petals V, I curving slightly distally in 

 some specimens. Interporiferous zones slightly wider than poriferous 

 zones; poriferous zones very wide, outer pore of pore pair slitlike, 

 very elongated, inner pore slightly elongated obliquely. 



Adoral interamhulacra. — Two plates at peristome in each inter- 

 ambulacrum preceded by regularly alternating plates. 



Periproct. — Supramarginal, in contact with posterior oculars, elon- 

 gated longitudinally, in deep groove which extends to posterior 

 margin. 



Peristome. — Slightly anterior, pentagonal. 



Floscelle. — Bourrelets strongly developed, inflated. Phyllodes (text 

 fig. 15 for C. sinuatus) double pored, extremely long, extending 

 two-thirds length of ambulacrum on adoral side, with many pore 

 pairs arranged in three series in each half-ambulacrum : approxi- 

 mately 15 pore pairs in each series. 



Tnherculation. — Tubercles on adoral surface larger than on adapi- 

 cal surface. 



Occurrence. — Jurassic (Bajocian and Bathonian) of England, 

 France, Switzerland. 



Location of type specimen. — Unknown. 



Remarks. — Wright (1859, p. 363), Cotteau (1870, Pal. franc, 

 Jur., p. 192), and others have considered that Leske's C. plotii and 

 C. sinuatus are synonyms. The specimens referred to C. plotii came 

 from the Inferior Oolite in the Clypeus grit, which is uppermost 

 Bajocian, resting directly under the Zig Zag beds which Cifelli (1959, 

 p. 269) considers lowermost Bathonian, C. sinuatus is supposedly 

 from the Bathonian Greater Oolite. The specimens I have studied 

 from the Greater Oolite are smaller (pi. 7, figs, i, 2; pi. 8, fig. 4), 

 have a more depressed adoral surface, and posterior petals curving 

 distally, as opposed to the Inferior Oolite specimens (pi. 7, fig. 6) 

 with a large test, flat adoral surface, and straight posterior petals. 

 Probably these specimens represent two separate species, the large 



