42 INTRODUCTION TO ZOOLOGY. 



length of time that would be reqtnsltc, with a certain number 

 of persons, for counting tliis number. Allowing that one 

 person could count a million in seven days, which is barely 

 possible, it would have required that 80,000 persons could 

 have started at the creation of the world, to complete the 

 enumeration at the present time!" 



" What a stupendous idea this fact gives of the immensity 

 of creation, and of the bounty of Divine Providence in furnish- 

 ing such a profusion of life, in a region so remote from the 

 habitations of men ! But if the number of animals in a space 

 of two miles square be so great, what must be the amount 

 requisite for the discolouration of the sea, through the extent 

 of })erhaps twenty or thirty thousand square miles?" * Even 

 if the learned author, from whom this extract is taken, should 

 prove to be incorrect in his supposition as to the depth to 

 which the Medusa; extend, the spirit of his argument would 

 remain unshaken. His observations prove, that they people, 

 in countless multitudes, tracts of ocean which, without them, 

 would be uninhabited, thus filling its vast expanse with life, 

 and with the enjoyment by which life is accompanied; while, 

 at the same time, they furnish an inexhaustible supply of food 

 to whales and other cetacea, and many of the less bulky in- 

 habitants of the deep. Thus, minute though they are, tiiey 

 indirectly contribute to the welfare of man, and exercise an 

 influence on his social relations. 



CLASS RADIARIA— CONTINUED. 

 Order Echinodermata, or Star-Fishes. 



" As there are stars in the sky, so there are stars in the sea." — I.ixk. 



The second gi-eat division of the rayed animals comprises all 

 those which have a hard coriaceous integument {Fig. 28), 

 covered, in some species, with prickles like those of the 

 hedgehog. The word "■Echinus'''' means hedgehog; the 

 word " clerma,^'' a coat or covering. Hence the compound 

 word '■'■ Echinodermata'''' is an appropriate and characteristic 



• Scoresby's Arctic Regions, vol. i. page 179. 



