STAR-FISHES. 



101 



commonest of objects on every shore, is an excellent 



lisation. There are five distinct radiating arms, as in the 

 Brittle-star ; but they are massive, thick, short, and com- 

 paratively inflexible, while the disk or central undivided 

 portion bears a much greater proportion to the whole 

 expanse. 



But a change much more remarkable has been effected 

 in the manner of progression. In the Feather-star, as we 

 have seen, the motion is truly natatory, performed by the 

 alternate contraction and expansion of its inflated arms, 

 aided, perhaps, by the lateral pinna?, with which these are 

 furnished. In the Sand-stars and Brittle-stars the swim- 

 ming faculty is lost ; the animal drags itself over the 

 stones and even up perpendicular surfaces by its flexible 

 arms, the spines of which catch hold of every projection 

 and roughness. In the Star-fishes a new set of organs is 

 developed, highly curious in their nature, and, like all 

 other of the works of God, well qualified for their 

 office. 



Let lis go to the first Five-finger we see lying on the 

 shingle, and turn it over. We now see that each of the 

 five rays has a deep furrow running along its under sur- 

 face, proceeding from the mouth in the centre of the disk, 

 even to the tip of the arm. This furrow has been fanci- 

 fully named the ambulacrum, or avenue. 



Now let us, in the plentitude of our compassion, take 

 the poor wretch from the stones where he lies broiling in 

 the burning sun, and, bearing him home, gently place him 

 in a glass vessel of cool sea- water. Our virtue will be its 



;ample of this order 



tendency to centra- 



