120 THE HISTORY OF CREATION. 



myriopods, spiders, and Crustacea, but besides these, a large 

 number of the worms, especially the ringed worms. The 

 third main division comprises the molluscous animals 

 (Mollusca) — slugs, snails, mussels, and some kindred groups. 

 Finally, the foui-th and last circle of the animal kingdom 

 comprises the various radiated animals (Radiata), which at 

 first sight difi'er from the three preceding types by their 

 radiated, flower-like form of body. For while the bodies of 

 molluscs, articulated animals, and vertebrated animals consist 

 of two sjrmmetrical lateral halves — of two counterparts or 

 antimera, of which the one is the mirror of the other- — the 

 bodies of the so-called radiated animals are composed of 

 more than two, generally of four, five, or six countei-parts 

 grouped round a common central axis, as in the case of a 

 flower. However striking this difierence may seem at first, 

 it is, in reality, a very subordinate one, and the radial form 

 has by no means the same importance in all " radiated 

 animals." 



The establishment of these natural main groups or types of 

 the animal kingdom by Bar and Cuvier was the greatest 

 advance in the classification of animals since the time of 

 Linngeus. The three groups of vertebrated animals, articu- 

 lated animals, and molluscs are so much in accordance with 

 nature that they are retained, even at the present day, little 

 altered in extent. But a more accurate knowledge soon 

 showed the utterly unnatiu-al character of the group of the 

 radiated animals. Leuckart, in 1848, first pointed out that 

 two perfectly distinct t3rpes were confounded under the 

 name, namely, the Star-fishes (Echinoderma) — the sea-stars, 

 lily encrinites, sea-urchins, and sea-cucumbers ; and, on the 

 other hand, the Animnal-'plants, or Zoophytes (Coelenterata, 



