ECHINUS. 127 



very minute, were now issuing from others, and continued still ad- 

 vancing. 



In such a case as the present the multitude of parts is so great that 

 the observer is confounded in attempting to watch the progress of any 

 portion of them. 



The specimen survived until May of the succeeding year, or twenty- 

 two months in whole. 



Another specimen, somewhat smaller, taken in January, fed plenti- 

 fully at intervals. In a month it seemed to be casting the spines. Many 

 shorter than their fellows wei'e interspersed among those remaining. 

 But in two months almost the whole of those originally investing the 

 specimen had fallen. 



Meantime new ones were advancing. When totally divested of 

 spines in another month, the subject still fed readily. There the extent 

 of the suckers equalled the diameter of the shell. 



From many specimens perishing, the loss of the spines either induces 

 or indicates disease. It may be nevertheless a natural process, or con-, 

 sequent on some external injuiy. 



It appears, however, that a great, if not a total loss, and regenera- 

 tion of the spines, naturally ensues towards the end of the year, or 

 during the months immediately succeeding. 



About that time much irregularity is seen among them. Many 

 are infinitely smaller than others, whether from the earlier or later origin 

 of one portion of them ; and many Echini are recovered from the sea 

 whose entire coating is both shorter and thinner than at other periods. 

 There are some whei-ein the disparity among the s^jines themselves is ex- 

 traordinary. 



It is only when divested of the whole of its superficial covering that 

 the shell can be distinctly seen, or that the form, proportions, and ar- 

 rangement of all its parts, are exposed to the view of the beholder in 

 much and interesting variety. 



When divested of the spines the shell bears some resemblance to an 

 orange. The surface is divided into five larger and five smaller compart- 

 ments. It is covered by an epidermis, either of uniform or variegated 

 colours, whereon much of its beauty depends. Sometimes the spines are 



