136 ECHINODERMATA. 



Of these, three or four different kinds are sufficiently definite. 

 1. Such as are long, slender, and slightly incurved. 2. Those of broad 

 paddle-shape, with a short neck. 3. Spines of a narrow paddle-shape, 

 with a long neck. 



The upper surface of the finest white specimens of this Echinus, is 

 distinguished by three purple rings, but not alike conspicuous in all. 



The mouth, like that of the preceding animal, QieSptttanffUS pttrpurew, 

 opens in the under surface, amidst a purple star, consisting of forty or 

 fifty suckers, as obvious in the best specimens, but less distinct in others. 

 The vent is in the extremity. 



Unlike the Spafatir/tis piirpurcux, the lower part of the animal is 

 thicker than the higher, and its general aspect somewhat different. 



All the specimens, that is between twenty and thirty, which I have 

 seen, were either white or sulphur-yellow. 



The suckers of this species are beautiful floriform objects. Their 

 flattened head or disc, composed of numerous papilla), environed by a 

 circular margin, is borne on a flexible stalk. Plate XXXIII. figs. 0, 7, 

 enlarged ; magnified, fig. 8. The colour varies from crimson to lighter red. 



The shell of the Spatangnx flavt'smu is wonderfully thin and brittle. 

 It seems insufficient for any resistance ; actually crumbling almost to 

 dust among the fingers of any one attempting to cleanse it of the spines. 



This creature burroAvs in the sand at various depths, somewhat 

 above low water-mark ; but it seems rather a scarce production. 



On one occasion, while specimens were undergoing manipulation, 

 :i slender cartilaginous looking organ extended about two inches from 

 among the spines of one. It terminated in an expanding star of about 

 fifteen purplish, short, slender, unequal pointed filaments, remaining in 

 considerable action ; but I was unable to satisfy myself in any manner 

 regarding its real structure or use. 



l'l..\TF XXXIII. 



Fic. 1. Spatangusflavegcens. 



2. Unilur surface. 



3. Shell divested of the spine?, under snit'acc, shewing the position and 

 form of the mouth and shield. 



