ECHINODERMATA. 43 



thought was identical with Cidaris Bouchardii ; but on making a careful examination of 

 the ambulacral and the inter-ambulacral plates, the only portions of the test I have seen 

 with those of that species, I am inclined to think them distinct. The plates are thick 

 and deep (PI. V, fig. 7 a, b) ; the areolas are circular, with a complete circle of scrobicular 

 granules around them ; the bosses are raised a little way above the margin of the areola, 

 and the summits are feebly crenulated ; the tubercle is large, and supported on a short 

 stem ; the miliary zone is wide and concave, and there are six or eight rows of coarse 

 granules filling up the same. The ambulacral areas are narrow, with two rows of 

 marginal granules, one granule being opposite each pair of holes ; the poriferous zones 

 are narrow, the holes are round, and the septum has a tubercle developed on its surface ; 

 there are seventeen pairs of holes opposite one large tubercular plate. The spines, 

 associated with the plates in the same bed, are well preserved (PI. V, fig. 7 d, e) ; 

 the acetabulum and head are small ; the neck is long and smooth ; and the stem is 

 covered with granules, which are arranged in lines that are not longitudinal, but slightly 

 waved. Most of the fragments appear to have been drifted ; they are more or less 

 covered with a species of small serpula, which seems to have been abundant in the seas of 

 that period. 



Affinities and differences. — This species very much resembles Cidaris Bouchardii, but 

 its tubercles are proportionately larger, and the areolas are smaller ; the scrobicular circle 

 of granules is more defined, the miliary zone contains a greater number of granules, 

 and there is a granular space between some of the scrobicular circles which does not 

 exist in Cidaris Bouchardii. 



Locality and Stratigraphical position. — The plates and spines of this species have been 

 collected from the Bradford Clay, near the Tetbury-road Station of the Great Western 

 Railway, associated with Bhynchonella concinna, Sow., Terebratula cardium, Lamarck, 

 Terebratula diyona, Sow., and other Bradford Clay forms. 



