Dr. T. Wright on the Cidaridse of the Oolites. 277 



like manner two ranges of small tubercles, about twenty in each 

 range, occupying the centre of the plates ; the tubercles are raised 

 on inconsiderable mammillary eminences surrounded by smooth 

 areolae, and encircled by a zone of small granules ; the intertu- 

 bercular spaces of both arese are covered with similar small granula- 

 tions; there are a few irregular secondary tubercles about the base, 

 but none on the sides of the interambulacral or ambulacral arese ; 

 the poriferous avenues are narrow, and occupied by numerous close- 

 set pores arranged in triple oblique pairs ; the basal angle is ob- 

 tuse, and the base concave ; in this region the tubercles are largest, 

 and a few additional ones are introduced at each side of the cen- 

 tral range; the mouth-opening is moderate, being y'^ths of an inch 

 in diameter ; it is nearly of a cii'cular form, the marginal notches 

 being of inconsiderable depth ; the ovarial and ocular plates are 

 small and preserved ; in some of the smaller specimens the madi"e- 

 poriform plate is larger than the pairs of ovarials ; the anus is 

 situated before the single plate, and to the right side, and is 

 therefore slightly eccentrical. The spines are unknown. 



Affinities and differences. — The comparative smoothness of the 

 test, and the absence of secondary tubercles, with the smallness 

 of the marginal notches in the mouth-opening, form diagnostic 

 characters by which we distinguish E. serialis from E. perlatus ; 

 the median depression between the two columns of interambulacra 

 is likewise absent in this species. 



Locality and stratigraphical range. — This species has been col- 

 lected from the Inferior Oolite at Shurdington and Dundry Hills ; 

 the specimen from the latter locality is the one which has served 

 for our description, the parts of the test which are broken being 

 fortunately present in the smaller Urchin from the former loca- 

 lity ; the Swiss specimens were found in the " Terrain k chailles " 

 at Fringeli (Canton of Solem-e), where it is very rare. 



History. — First found by M. Gressly and figured and described 

 by M. A^assiz in his ' Echin. Fossiles ' ; we are not aware of its 

 having been noticed before as a British species. 



Echinus granularis (Wright), n. s. 



Test depressed, pentagonal ; ambulacral arese with two rows of 

 tubercles ; interambulacra with eight rows of tubercles, at the 

 base and lower third of the arese diminishing in size and num- 

 ber from six to fom* rows towards the apex ; mouth large with 

 marginal indentations ; anus central ; ovarial and ocular plates 

 small. 



Height Yyths of an inch, transverse diameter 1^ inch. 

 Description. — This Urchin is distinguished from the foregoing 

 species by its depressed poles and pentagonal form, arising from 



