32 CIDARIS. 



Lias of Ilminster, and was found associated with Ammonites serpeniinus, Schlotheim, 

 Ammonites annulatus, Sowerby, and other Upper Lias fossils. The fragment figured was 

 the only one ever found. 



B. Species from the Inferior Oolite. 



Cidaris Fowleri, Wright. PI. I, fig. 4 a, b, c, d, e. 



Cidaris coronata. Murchison's Geology of Cheltenham, 2d ed., by Buckman and 

 Strickland, p. 73. 



— — Morris's Catalogue of British Fossils, Inf. Oolite, Cotteswold Hills, 



1st ed., p. 49. 



— Fowleri. Wright, Annals and Magazine of Natural History, 2d series, vol. viii, 



p. 246, pi. 11, fig. 5 a,b. 



— — Desor's Synopsis des Echinides Fossiles, p. G, tab. 3, fig. 13. 



— — Morris's Catalogue of British Fossils, 2d ed., p. 74. 



Test spheroidal, depressed at both poles ; ambulacral areas prominent, flat, narrow, 

 and slightly undulated, with two marginal rows of small, equal-sized, close-set granules, 

 and two rows of central, irregular, and almost microscopic granules, with still smaller 

 granules interspersed between them ; poriferous zones broad, each as wide as the ambu- 

 lacra ; pores oblong, set wide apart, with a thick septum between the two pores of each 

 pair ; inter-ambulacral areas with two rows of primary tubercles, six to eight in each row, 

 all the areas surrounded by a complete scrobicular circle of granules ; miliary zone wide, 

 filled up with small close-set granulations ; spines large, covered with irregular rows of 

 forward-directed prickles. 



Dimensions. — Height one inch and one tenth, transverse diameter one inch and 

 eight tenths ; two crushed specimens, the relative dimensions of which, therefore, cannot be 

 accurately ascertained, measure considerably more. 



Description. — This beautiful Cidaris, which, when first discovered, more than fifteen 

 years ago, was supposed to be the Cidaris coronata, Goldfuss, and was catalogued as such 

 in the works cited in the synonyms of the species. Apart from the organic characters to 

 be pointed out in the sequel, it is a form which has hitherto only been found in the 

 Inferior Oolite, whilst Cidaris coronata, Goldf... as constantly characterises the upper 

 zone of the middle division of the Jurassic group. In the Swiss Jura, for example, it is 

 found in the " terrain a chailles," a local formation, the greatest similarity to which, it 

 appears, is the lower Calcareous Grit of England ; in the Coral Rag, or Argovien, of 

 Randen, of Birmansdorf, of the valley of the Birse, and of the same stage in Bavaria and 



