£$6 THE COMMON SEA-UI? CHIN. 



cular form ; and the whole body is supported entirely 

 by a set of upright bones or columns. On the out- 

 side of the shell is a prodigious number of sharp 

 moveable spines, of a dull violet and greenish colour, 

 curiously articulated, like ball or socket, with tuber- 

 cles orr the surface, and connected by strong liga- 

 ments to the skin or epidermis with which the shell- 

 is covered. The spines are the instruments by which 

 the animal conveys itself at pleasure from one place 

 to another; and by means of these it is enabled to 

 move at the bottom of the water with great swiftness. 

 It generally employs those about the mouth for this 

 purpose, keeping that opening downward; but it is 

 also asserted to have the power of moving forward by 

 turning on itself like a wheel*. When any thing 

 alarms these animals, they immediately move all 

 their spines toward it, and wait an attack, as an army 

 of pikemen would with their weapons. The num- 

 ber of muscles, fibres, and other apparatus necessary 

 to the proper management of these must be very 

 great, and are exceedingly wonderful. So tenacious 

 are the Sea-urchins of the vital principle that, on 

 openingoneof them, it is no uncommoncircumstance 

 to observe the several parts of the broken shell move 

 off in different directions. The ancients, according 

 to Oppian, gave credence to a circumstance much 

 more wonderful than this. 



Sea urchins, who their native armour boast, 

 All stuck with spikes, prefer the sandy coast. 



* Wallis, 1*. 393, 



