ECHINODEKMATA 



71 



inflexible legs, upon which the Echinus rolls itself from 

 place to place, or by their assistance it can bury itself in 

 the sand with the greatest facility. But these wonderfully- 

 constructed animals are by no means confined to this mode 

 of progression; for impossible 

 as it might seem from their 

 outward appearance, they are 

 able to climb rocks in search 

 of food, and thus obtain the 

 corallines and shell-fish upon 

 which they principally feed. 

 To enable them to effect this, 

 their shell is perforated with 

 ten rows of gmall orifices, ex- 

 tending from one pole to the 

 other, like the lines of longi- 

 tude upon a globe, through 

 which long suckers issue similar 

 in structure to those of the star- 

 fish, but long enough to extend beyond the points of the 

 spines; so that, by their assistance, the Sea-Urchin not 

 only scales the cliff, but creeps along pendent from the 

 roofs of submarine caverns. 



FlG. 47- GREEN-PEA URCHIN. 



FlG. 48. FIGURE OF STICKER OF TJRCHIX, 



The number of these suckers is very great : in a mode- 

 rate-sized Urchin, Professor Forbes reckoned sixty-two 

 rows of pores in each of the ten bands ; as there are three 

 pairs of pores in each row, their number multiplied by 

 six and again by ten would give three thousand seven 



