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Contributions to the Paleontology of Gloucestershire : A descrip- 

 tion, with Figures, of some new Species of Echinodermata from 

 the Lias and Oolites. By THOMAS WRIGHT, M.D. &c., Pro- 

 fessor of the Natural Sciences in the Cheltenham Grammar 

 School. 



READ 4xn MAY 1852. 



Cidaris Edwardsii t Wright. PI. I. fig. 1, a-f. 



Test crushed, the form therefore unknown. Ambulacral areas 

 narrow, with two rows of small perforated tubercles, and 

 smaller perforated ones interspersed amongst them ; interam- 

 bulacral areas about four times the width of the ambulacral, 

 having two rows of large tubercles with confluent areolas ; the 

 primary spines long, with a compound structure ; the secondary 

 spines short with blunt apices, the surfaces of both sculptured 

 with delicate longitudinal lines ; mouth armed with powerful 

 jaws, each with three prominent tricarinated ridges. Upper 

 part of the test and ovarial disc unknown. 



Description. It is much to be regretted that no other speci- 

 men of this noble Urchin but the one before us has been ob- 

 tained from the Lias of Gloucestershire, and as the specimen 

 exhibits only the lower half of the test, many points of its ana- 

 tomy remain unknown; enough of its structure, however, is 

 shown to enable us to point out some important affinities and 

 differences in this rare species. 



The narrow ambulacral areas are provided with two rows of 

 small perforated tubercles, amongst which smaller tubercles are 

 irregularly scattered; these tubercles all support short stout 

 spines with a minutely sculptured surface, and which are abun- 

 dantly preserved in situ on the specimen. The wide poriferous 

 avenues are occupied with large oblong pedal pores with very 

 thin partition-walls between them, a circumstance which forms 

 a good diagnostic character between C. Edwardsii and C. Fowleri t 

 which it very much resembles in many points of structure, the 

 pores in C. Fowleri being small and separated by thick partition- 

 walls. The interambulacral areas are four times the width of 

 the ambulacral, and are occupied by two rows of large tubercles 

 set closely together in a vertical direction, so that the areolas 

 above and below are quite confluent throughout. 



VOL. II. C 



