RADIARIES. 209 



or fix itself to any substance ; it is thought also, 

 as they are perforated, that it uses them to absorb 

 the water for respiration. The length of these 

 suckers or tentacles, for so they may be also 

 called, when they are fully extended, is always 

 greater than that of the spines, so that they may 

 serve as so many anchors to fix the animal and 

 enable it to resist the mass of waters that press 

 upon it. They are stated to be more numerous 

 near the mouth than in other parts, by which 

 arrangement Divine Wisdom has fitted them to 

 maintain a horizontal position, which is their 

 natural one. These suckers fix the animal so 

 firmly to the rocks, that it is with the greatest 

 difficulty, and seldom without crushing the shell, 

 that they can be separated. 



The most powerful and complex organs with 

 which the Creator has gifted the Echinidans 

 are their jaws and teeth. Their mouth has 

 adapted to it a remarkable frame- work, con- 

 sisting of five pieces, corresponding with five 

 segments, into which the shell may be divided ; 

 each of these pieces forms an arch, 1 and the 

 whole a pyramidal frame, which was compared 

 by Aristotle to a lanthorn without a skin. To 

 these are attached the moveable part of the 

 apparatus, consisting of five jaws, each con- 

 taining a long tooth, 2 the teeth converging in 



1 PLATE III. Fio.S.rf. 2 7iirf,FiG. 10, 11. 



VOL. I. P 



