UPPER, OR FLINTY CHALK. 189 



they seize and convey to their mouth by means of the tentacula, the 

 spines being the instruments of motion*. 



Various systematical arrangements of the echini have been formed by 

 naturalists f ; that of Leske, adopted by Mr. Parkinson, is followed in the 

 subjoined description of the Sussex specimens. 



CiDARis (the turban). This family comprises those echini which are of 

 an hemispherical, globular, or oval form, with avenues of pores diverging 

 equally on aU sides from the vent to the mouth ; vent vertical, mouth 

 central. 



31. Cidaris saxatilis. Org. Rem. Vol. iii. PI. 3, fig. 1. 

 Hemispherical, depressed, with ten porous ambulacra, and two rows of 



small nearly equal tubercles, or papUlEe, on each area . 



This is a smaU species, seldom more than 07 inch in diameter. 

 Locahties. Bridgwick, and South-street chalk-pits, near Lewes. 



32. Cidaris papillata. Org. Rem. Vol. iii, PI. 1, fig. 9. 



Eound, rather depressed, divided by undulating biporous ambulacra 

 into five areee, each having two rows of tubercles disposed alternately, and 

 surmounted by perforated papillae, encircled by a distinct groove at their 

 base; the intermediate surface finely granulated. 



This beautiful fossil is well known to collectors ; it is rather rare in 

 Sussex. It occurs occasionally in the upper chalk, and impressions of its 

 plates and spines are sometimes observable on the flints and pebbles on 

 the sea shore. 



The spines of this species are slender, and delicately muricated; one of 

 them is represented in Tab. xvii. fig. 13. 



Localities. Upper chalk, near Lewes and Brighton. 



S3. Cidaris Konigii. Org. Rem. Vol. iii. Tab. i. fig. 10. 



Circular, much depressed, divided by porous ambulacra into five large 

 and five small areae. The lesser divisions ornamented with two rows of 



* Rees' Cycloptsdia. Art. Echinus. 



•f- Mr. Konig has constructed an excellent arrangement of the fine suite of echini in the 

 British Museum ; and I much regret, that unavoidable circumstances have prevented me from 

 adopting it on the present occasion. 



