13-2 . THE HARMONIES OF NATURE. 



CHAPTEK XVIII. 



ECHINODERMATA. 



Primeval Sea-stars. Feather-stars. Snake-stars. Star-fishes. Their Suckers 

 and Mode of Locomotion. Their Skeleton. Their Victims and their Enemies. 

 Sea-Urchins. Structure of their Shell. Their Dental Apparatus. Pedicellarise, 

 or Sea-Cucumbers. Metamorphoses of the Echinodermata. 



AT that far-distant period of the earth's history when the 

 swampy lowlands were covered with those thickets of calamites 

 and stigmarias whose remains have given birth to the coal strata 

 of the present day, the bottom of the ocean was paved in many 

 places with crinoid star-fishes, whose bodies, branching out into 

 delicately feathered bifurcated arms, were affixed like flowers 

 to a slender articulated stalk. 



Their petrified skeletons, imbedded in countless numbers in 

 many of the calcareous strata of our island, bear witness to their 

 ancient importance ; but the beautiful and antique race of these 

 Lily Encrinites and Pentacrinites is now reduced to but one 

 single representative in the British seas the rosy feather-star, 

 whose long and delicately fringed ray, and deep rose colour 

 dotted with brown, may serve to give us an idea of the beauty 

 of the submarine landscapes at the time when the bottom of the 

 sea was peopled with gigantic specimens of the same class. 

 Attached in its infancy to a stalk like its mightier predecessors, 

 it swims freely about at a later period, by alternately contract- 

 ing and extending its closely-feathered arms. It is found all 

 round our coasts, and is frequently brought up in from ten to 

 twenty fathoms water, attached to different kinds of seaweed, 

 which it lays hold of by means of the claws which tip the fila- 

 ments that clothe its body. 



Thus the crinoid star-fishes have mostly disappeared, but the 

 asteroidea, forming the two great subdivisions of the snake- 



