SEA-UBCHINS AND SEA-CUCUMBERS. 295' 



at your eye, over the shell, you perceive that the spines, 

 though all formed on a common model, differ considerably 

 in the detail of their form. I have shown you what may 

 be considered the average shape; but in some, especially 

 the finer ones that clothe the sides, the club is slender and 

 pointed ; in others, as in those behind the mouth, which 

 are the largest and coarsest of all, the club is dilated 

 into a long flat spoon ; while in the long, much-bowed 

 spines which densely crowd upon the back, the form is 

 almost uniformly taper throughout, and pointed. 



The animal sinks into the sand mouth-downwarcls. The 

 broad spoons behind the mouth come first into requisi- 

 tion, and scoop away the sand, each acting individually, 

 and throwing it outwards. Observe how beautifully they 

 are arranged for this purpose ; diverging from the central 

 line, with the curve backwards and outwards. Similar 

 is the arrangement of the slender side-spines ; their curve 

 is still more backwards, the tips arching uniformly 

 outwards. They take, indeed, exactly the curve which 

 the fore-paws of a mole possess (only in a retrograde 

 direction, since the Urchin sinks backwards), which has 

 been shown to be so effective for the excavating of the 

 soil, and the throwing of it outwards. Finally, the long 

 spines on the back are suited to reach the sand on each 

 side, when the creature has descended to its depth, and 

 by their motions work it inward again, covering and 

 concealing the industrious and effective miner. 



Thus we have another instance added to the ten thou- 

 sand times ten thousand, of the wondrous wisdom of God 

 displayed in the least and most obscure things. "All 

 Thy works shall praise Thee, Lord ! " (Ps. cxlv. 10). 



There is an order of animals which naturalists put in 

 the same category as the Sea-Urchins, but which an un- 

 scientific observer would regard as possessing little or no 

 affinity with them. Some are like long, soft, and fleshy 

 worms, and others, which come the nearest to the crea- 



