250 Dr. T. Wright on the Cidarida? of the Oolites. 



Wahlen, and Gunsberg in the canton of Soleure, and in the 

 white corallian of Hoggerwald *. 



History. — This beautiful species was long ago figured by 

 Parkinson in his f Organic Remains/ afterwards it was most 

 accurately figured and described by Goldfuss in his ' Petrefacta/ 

 and subsequently by Agassiz, Phillips, and Cotteau, in their re- 

 spective works. 



Cidaris propinqua, Minister. PL XL fig. 6. 



Syn. Cidarites propinquus, Miinst. ; Goldfuss, Petrefact. German. 



p. 119. t. 40. fig. 1, 2 ; Agassiz, Prodrom. Echin. p. 21 ; Echi- 



noderm. Foss. Suisse, p. 62. t. 21. fig. 5-10 ; Desmoulins, Tabl. 



Synop. p. 328, No. 17. 

 Cidaris monilifera, Agassiz, Catal. Syst. Ectyp. Neoc. p. 9. 

 Cidaris coronata,Y&Y. minor, Agassiz andDesor, Cat. raisonne desEchi- 



nides ; Cotteau, Echinides Foss. du Depart, de PYonne, p. 104. 



Test thick, circular, and depressed at the poles ; ambulacral area? 

 narrow, sinuous, and furnished with two rows of small round 

 prominent granules ; interambulacral area? with two rows of 

 large prominent tubercles, six in each row, raised on small 

 mammillary eminences with smooth summits ; " spines with a 

 short neck and a thick granulated stem ;" apical disc unknown. 

 Height T 6 oths of an inch, transverse diameter 1 inch. 

 Description. — This Urchin resembles in many points the pre- 

 ceding species, but exhibits characters very distinct from it. The 

 ambulacral area? are extremely narrow and serpentine, having 

 two rows of small prominent granules arranged on the margins 

 of the area?, with a few central microscopic ones between them 

 about the equator. The pores are placed in rather deep winding 

 avenues, closely and obliquely together in single pairs. The in- 

 terambulacral area? are nearly five times the width of the ambu- 

 lacral, and furnished with two rows of tubercles, six in each row ; 

 they are large, prominent, slightly perforated, and nearly sphe- 

 rical ; the mammillated eminences on which they are supported 

 being disproportionately small, and having smooth and convex 

 summits, unlike the crenulated summits observed in the mamma? 

 of other Oolitic Cidarida. The specimen before us is too much 

 injured to enable us to state whether any rudimentary sculpture 

 surrounds the summits of the mamma? on the superior surface 

 of the test, as is the case in the Swiss and German specimens. 

 The areola? are shallow and nearly of a circular form, their mar- 

 gins being encircled by a wreath of twelve small round promi- 

 nent granules supported on little eminences, and forming a 

 distinct beaded boundary for each tubercle. The median space 

 down the centre of the area? is slightly concave, and filled with 

 * Agassiz, Echin. Foss. Suisse. 



