36 CIDARIS. 



BRACHIOPODA. 



Terebratula simplex, Buckraan. {Terebratula trigonalis, Lhwydd.) 

 Tercbr alula plicala, Buck man. 

 Terebratula submaxillata, Davidson. 



CEPHALOPODA. 



Ammonites corrugatus [Murchisona), Sowerby. 



This species is dedicated to our friend, Charles Fowler, Esq., who generously added to 

 our collection the fine specimen figured in detail. 



Cidaris Bouchardii, Wright. PI. I, fig. 2 a, b, c ; PL VIII, fig. 3 a, b, c. 



Cidaris elegans. Morris's Catalogue of British Fossils, 1st ed., p. 49, 1843. 



— Bouchardii. Wright, Annals and Magazine of Natural History, 2d series, vol. xiii, 



p. 163, pi. 11, fig. 2. 



Test circular, much depressed ; ambulacral areas narrow and flexuous ; poriferous 

 zones deep and narrow ; inter-ambulacral areas with two rows of primary tubercles, six to 

 seven in each row; areolas circular, deeply excavated, and entirely surrounded by an 

 elevated scrobicular circle of large granules ; a zigzag depression extends through the 

 centre of the inter-ambulacral areas ; centro-sutural line strongly marked. 



Dimensions. — A large specimen : Height, nine tenths of an inch ; transverse diameter, 

 one inch and seven tenths. A moderate-sized specimen : Height, eleven twentieths of 

 an inch ; transverse diameter, one inch and two tenths. 



Description. — This beautiful urchin was entered in the Catalogue of British Fossils as 

 Cidaris elegans, Goldfuss. A comparison, however, of several individuals of Cidaris 

 Bouchardii, with typical specimens of Goldfuss's species, kindly sent us by our friends, 

 Prof. Roemer, of Bonn, which he had identified with the original Cidaris elegans, Goldf., 

 in the Bonn Museum, and Dr. Fraas of Stuttgard, has enabled us to separate these two forms. 



The test of Cidaris Bouchardii is circular, and much depressed, from the great flatten- 

 ing of both of the upper and under surfaces ; the ambulacral areas are narrow, and much 

 undulated ; they have two marginal rows of small granules, with a few more minute ones 

 scattered irregularly between them ; the poriferous zones are narrow and slightly sunk ; 

 the holes are circular and contiguous, and are separated by a prominent granule rising 

 from the surface of the septum. (PI. I, fig. 2 c.) 



The inter-ambulacral areas are five times the width of the ambulacral (PI. I, fig. 2 a,b,c ; 

 PI. VIII, fig. 3 a, b) ; the primary tubercles are small, and from six to seven in each row ; 



